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2017 Vol. 2 No. 2: 9 1 © Under License of Creative Commons Attribution 3.0 License | This article is available in: http://www.imedpub.com/synthesis-and-catalysis-open-access/ iMedPub Journals http://www.imedpub.com Research Article DOI: 10.4172/2574-0431.100015 Synthesis and Catalysis: Open Access ISSN 2574-0431 Fatima Pardo-Tarifa 1,2* , Saúl Cabrera 2 , Margarita Sanchez- Dominguez 3 , Robert Andersson 1 and Magali Boutonnet 1 1 Royal Instute of Technology-KTH, School of Chemical Science and Engineering, Chemical Technology, Stockholm, Sweden 2 Universidad Mayor de San Andrés, Instuto del Gas Natural-IGN, Campus Universitario, La Paz, Bolivia 3 Centro de Invesgacion en Materiales Avanzados, S.C. (CIMAV), Unidad Monterrey, Monterrey, Mexico Corresponding author: Fama Pardo-Tarifa [email protected] Royal Instute of Technology-KTH, School of Chemical Science and Engineering, Chemical Technology, Teknikringen 42, SE-100 44 Stockholm, Sweden. Tel: +46 (0)8 790 8251 Citaon: Pardo-Tarifa F, Cabrera S, Sanchez-Dominguez M, et al. Synthesis and Characterizaon of Novel Zr-Al 2 O 3 Nanoparcles Prepared by Microemulsion Method and Its Use as Cobalt Catalyst Support for the CO Hydrogenaon Reacon. Synth Catal. 2017, 2:2. Introducon In the search for highly acve and selecve catalysts for the CO hydrogenaon reacon, all elements in metallic form from group VIII are able to chemisorb and dissociate CO and H 2 . However, only Ru, Co, Fe, and Ni are considered for use in commercial applicaons [1]. Fischer-Tropsch synthesis (FTS) is an exothermic reacon between H 2 and CO producing water and a wide variety of hydrocarbons in gas, liquid, and solid state used as fuels and chemicals [2,3]. Supported cobalt based catalysts have been used for FTS due to their higher acvity, high selecvity to linear hydrocarbons, and low acvity for water-gas shiſt (WGS) reacon [4,5]. The acvity and selecvity of cobalt catalysts are dependent on metal dispersion and reducon degree, support and promoter. The interacon of cobalt and alumina is high and promoters have been incorporated in order to avoid metal-support interacons [6,7]. Zirconium seems to increase the performance of Co/Al 2 O 3 catalysts [7-14]. Some authors aribute its promoon effect Received: March 05, 2017; Accepted: May 31, 2017; Published: June 15, 2017 Synthesis and Characterizaon of Novel Zr-Al 2 O 3 Nanoparcles Prepared by Microemulsion Method and Its Use as Cobalt Catalyst Support for the CO Hydrogenaon Reacon Abstract For the first me binary Zr-Al oxide nanoparcles were synthesized by co- precipitaon in water-in-oil microemulsion. For comparison, a similar material was prepared by Zr impregnaon on commercial alumina. Aſter calcinaon, these materials and unpromoted alumina were used as cobalt catalyst supports to study and compare their structural characteriscs and catalyc behavior in CO hydrogenaon reacon. The supports and final cobalt catalysts were characterized by X-ray diffracon (XRD), N 2 physisorpon, scanning and transmission electron microscopy (SEM and TEM), temperature programmed reducon (TPR) and H 2 chemisorpon. The material synthesized by microemulsion (Zr-Al 2 O 3 (ME)) presented homogeneous nanoparcles with highly dispersed zirconium, textural porosity with narrow pore size distribuon and high surface area. On the other hand, the material prepared by Zr impregnaon on Al 2 O 3 (Zr-Al 2 O 3 (IM)) produced a nonhomogeneous material with low Zr distribuon and structural porosity. The cobalt deposion on these supports seems to be affected by the presence of zirconium. In the presence of highly dispersed Zr on alumina, the cobalt interacon with the support is higher. On the other hand, the presence of ZrO 2 islands on alumina avoids the cobalt-support interacon favoring the cobalt reducon degree, which makes a more acve catalyst in the tested reacon. The final catalysts were tested in CO hydrogenaon, and a higher CO conversion was obtained with increased Co° availability on the catalyst surface. Furthermore, the selecvity was affected by the CO conversion and the physico-chemical properes of the catalyst. This study gives highlights on the synthesis of highly uniform bimetallic nanoparcles used as support for cobalt catalysts and their applicaon. Keywords: Zr-promoter; Zr-Al 2 O 3 ; Water-in-oil; Microemulsion method; Cobalt catalyst; Co 3 O 4 reducibility; CO hydrogenaon

Synthesis and Characterization of Novel Zr-Al2O3 ... Prepared2 by Microemulsion Method and Its Use as Cobalt Catalyst Support for the CO Hydrogenation Reaction. Synth Catal. 2017,

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Page 1: Synthesis and Characterization of Novel Zr-Al2O3 ... Prepared2 by Microemulsion Method and Its Use as Cobalt Catalyst Support for the CO Hydrogenation Reaction. Synth Catal. 2017,

2017Vol 2 No 2 9

1copy Under License of Creative Commons Attribution 30 License | This article is available in httpwwwimedpubcomsynthesis-and-catalysis-open-access

iMedPub Journalshttpwwwimedpubcom

Research Article

DOI 1041722574-0431100015

Synthesis and Catalysis Open AccessISSN 2574-0431

Fatima Pardo-Tarifa12Sauacutel Cabrera2Margarita Sanchez-Dominguez3Robert Andersson1 and Magali Boutonnet1

1 RoyalInstituteofTechnology-KTHSchoolofChemicalScienceandEngineeringChemicalTechnologyStockholmSweden

2 UniversidadMayordeSanAndreacutesInstitutodelGasNatural-IGNCampusUniversitarioLaPazBolivia

3 CentrodeInvestigacionenMaterialesAvanzadosSC(CIMAV)UnidadMonterreyMonterreyMexico

Corresponding author FatimaPardo-Tarifa

pardokthse

RoyalInstituteofTechnology-KTHSchoolofChemicalScienceandEngineeringChemicalTechnologyTeknikringen42SE-10044StockholmSweden

Tel +46(0)87908251

Citation Pardo-TarifaFCabreraSSanchez-DominguezMetalSynthesisandCharacterizationofNovelZr-Al2O3 NanoparticlesPreparedbyMicroemulsionMethodandItsUseasCobaltCatalystSupportfortheCOHydrogenationReactionSynthCatal201722

IntroductionInthesearchforhighlyactiveandselectivecatalystsfortheCOhydrogenationreactionallelementsinmetallicformfromgroupVIII are able to chemisorb anddissociateCOandH2Howeveronly Ru Co Fe and Ni are considered for use in commercialapplications[1]Fischer-Tropschsynthesis(FTS)isanexothermicreactionbetweenH2andCOproducingwaterandawidevarietyofhydrocarbonsingasliquidandsolidstateusedasfuelsandchemicals [23] Supported cobalt based catalysts have been

usedforFTSduetotheirhigheractivityhighselectivitytolinearhydrocarbonsandlowactivityforwater-gasshift(WGS)reaction[45]TheactivityandselectivityofcobaltcatalystsaredependentonmetaldispersionandreductiondegreesupportandpromoterTheinteractionofcobaltandaluminaishighandpromotershavebeen incorporated inorder toavoidmetal-support interactions[67]

Zirconium seems to increase the performance of CoAl2O3 catalysts [7-14] Some authors attribute its promotion effect

ReceivedMarch052017 Accepted May312017Published June152017

Synthesis and Characterization of Novel Zr-Al2O3 Nanoparticles Prepared by Microemulsion Method and Its Use

as Cobalt Catalyst Support for the CO Hydrogenation Reaction

AbstractFor the first time binary Zr-Al oxide nanoparticles were synthesized by co-precipitation in water-in-oil microemulsion For comparison a similar materialwaspreparedbyZrimpregnationoncommercialaluminaAftercalcinationthesematerials and unpromoted alumina were used as cobalt catalyst supports tostudy and compare their structural characteristics and catalytic behavior in COhydrogenationreactionThesupportsandfinalcobaltcatalystswerecharacterizedbyX-raydiffraction (XRD)N2physisorption scanningand transmissionelectronmicroscopy (SEM and TEM) temperature programmed reduction (TPR) andH2 chemisorption The material synthesized by microemulsion (Zr-Al2O3 (ME))presentedhomogeneousnanoparticleswithhighlydispersedzirconiumtexturalporositywithnarrowporesizedistributionandhighsurfaceareaOntheotherhandthematerialpreparedbyZrimpregnationonAl2O3(Zr-Al2O3(IM))produceda nonhomogeneous material with low Zr distribution and structural porosityThecobaltdepositionon thesesupports seems tobeaffectedby thepresenceof zirconium In the presence of highly dispersed Zr on alumina the cobaltinteractionwiththesupport ishigherOntheotherhandthepresenceofZrO2 islands on alumina avoids the cobalt-support interaction favoring the cobaltreductiondegreewhichmakesamoreactivecatalystinthetestedreactionThefinalcatalystsweretestedinCOhydrogenationandahigherCOconversionwasobtainedwithincreasedCodeg availabilityonthecatalystsurfaceFurthermoretheselectivitywasaffectedbytheCOconversionandthephysico-chemicalpropertiesof the catalyst This study gives highlights on the synthesis of highly uniformbimetallicnanoparticlesusedassupportforcobaltcatalystsandtheirapplication

Keywords Zr-promoterZr-Al2O3Water-in-oilMicroemulsionmethodCobaltcatalystCo3O4reducibilityCOhydrogenation

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to the increaseofactive intermediates (-CH2-)whichcausesanenhancementofthecatalystactivityandtheselectivitytolong-chainhydrocarbons[15]OtherauthorsfoundthatZrenhancesthe cobalt reducibility and consequently the catalyst activity[131617]OntheotherhandasimportantasthechoiceofthepromoteristhechoiceofthesynthesismethodConsideringtherelevance of the synthesis procedure for obtaining promotedalumina supports themicroemulsion preparationmethod is apromisingstrategyItallowsthesynthesisofhighlyhomogeneousmaterialswithcontrolledstructuralpropertiesandparticlesizes[18] Thismethodology has been employed for preparation ofmetal nanoparticles metal oxides andmixedmetal oxides forcatalytic and electrochemical processes [1920] The synthesisof inorganic nanoparticles in water-in-oil microemulsionsis driven by microscopic micelles that act as nanoreactorswhere the nanoparticle synthesis occurs A water-in-oil (WO)microemulsion isatransparentortranslucentsolutionwhich isopticallyisotropicandthermodynamicallystableItismadeupofdropletsofwatersurroundedbyacontinuousoilphasewheretheinterfacialtensionbetweenoilandwaterisovercomebytheuseofsurfactants[1821]

Thesynthesisofavarietyofbinarymetaloxideshasbeenstudiedascatalystssupportsforseveralcatalyticreactionsandhasshowngood results due to a high homogeneity and intimate binarymetal interaction Inadditionsmallsizeparticlesmaximizethesurfaceareaexposedtothereactantallowingmorereactionstooccur[2223]

BasedonthepresentedliteraturethepresenceofZrinaluminaincreasestheCOhydrogenationreactionhoweverthemethodof Zr incorporation intoAl2O3 has not been fully investigatedIn addition binary oxide nanoparticles used as supports havegiven good results in different application [24] To the bestof our knowledge no Zr-Al nanoparticles co-precipitated bymicroemulsion method have previously been prepared andstudied Therefore the synthesis of Zr-Al oxidenanoparticles isan adequate candidate for preparing cobalt catalyst supportsThe aim of thiswork is to synthesized aswell as to study thecharacteristicsofco-precipitatedZr-AlnanoparticlesAtthesametimeunderstandhowaffectthismaterialcomparedwithsimilaronesonthecobaltdepositionandfurtherapplicationascatalystforCOhydrogenationreaction

ExperimentalCatalyst preparationTheco-precipitationofZr-Alnanoparticleswasaccomplishedbymixingtwowater-in-oilmicroemulsionsolutions(microemulsion1(ME1)andmicroemulsion2(ME2))forcomposition(Table 1)ME1 contained Zr and Al precursors whileME2 contained theprecipitating agent NH4OH ME2 was added to ME1 dropwiseunder continuous stirring at 30degC until pH 9was reached Thesolutionwaskeptatconstantconditionsfor12htocompletethereaction The final solutionwas destabilizedwith acetone andthe solidproductwas separatedby centrifugationandwashedwithacetoneandwaterTheproductwas freeze-dried inorderto avoid the particles agglomeration Afterwards the productwascalcinedinairfor6hat550degC(heatingrate10degCmin)TheobtainedmaterialwaslabeledasZr-Al2O3 (ME)

For comparison Al2O3 and ZrAl2O3 were also prepared Acommercial pseudo-boehmite Al2O3 (Versal 250) was driedat 120degC for 5 h and calcined at 550degC for 6 h Afterwards anaqueous solutionofZrO(NO3)2waspreparedandadded to thetreatedaluminabyincipientwetnessimpregnation(molarratioAlZr=8)ThematerialwasthermallytreatedinthesamewayasZr-Al2O3(ME) TheobtainedmaterialwaslabeledasZr-Al2O3(IM)

Thecarriers(Zr-Al2O3 (ME)Zr-Al2O3(IM)andAl2O3)weredriedat120degCfor5hpriortothe12wtofcobaltdepositionAnaqueoussolution of Co(NO3)2middot6H2Owith volume equivalent to the porevolumeofeachsupportwasaddedtothesupportsdropwiseThecarrierporevolumewasdeterminedbyN2-adsorptiontechniqueAftermetal impregnation thematerials were dried for 6 h at120degC and calcined in air at 350degC for 10h (heating rate 1degCmin)ThefinalcatalystswerelabeledasCoZr-Al2O3(ME)CoZr-Al2O3(IM)andCoAl2O3

Catalyst characterizationX-raydiffraction (XRD) of the fresh sampleswas performedonaSiemensD5000X-raydiffractometerwithCuKαradiation(40kV30mA)Themeasurementswererecorded from10deg to90degin the 2θ range using a step size of 0020deg and a steptimeof12s for all the samples Thephaseswere identifiedby theEvasoftware(version130022007)CrystallitesizesofCo3O4werecalculated using the Scherrer equation and assuming sphericalparticles[25]TheCodegcrystallitesizewasestimatedfromCo3O4 using the formula d(Codeg)=075d(Co3O4) [2627] The analyseswere performed in a pressure interval between 20 and 510mm Hg Chemisorption isotherms were extrapolated at zeropressure in order to determine the adsorption of hydrogen[28] The stoichiometry assumptionwas that two cobalt atompermoleculeofhydrogenTheaverageparticlesizeofCodegwasestimatedaccordingtod(Codeg)H=96DmiddotDORassumingsphericalshape[2930]

BrunauerndashEmmetndashTeller (BET) surface area and porosity datawascollectedwithaMicromeriticsASAP20002020unit02gofthesampleswasoutgassedat250degCovernightpriortoanalysisThe data was recorded by N2 adsorption at liquid nitrogentemperatureatrelativepressuresbetween006and02

The reducibility of the catalysts was investigated by hydrogentemperature-programmedreduction(H2-TPR)[31]Thecalcinedcatalysts (015 g) were studied in a Micromeritics Autochem

ME Phase Compound(s) Composition (wt )

ME1

Oil Hexane 657Surfactant Brijcopy 264AqueousSolution

1M(AlCl36H2O-ZrO(NO3)2)molarratioofZrAl=18) 79

ME2

Oil Hexane 657Surfactant Brijcopy 264Aqueoussolution NH4OH38wt 79

Table 1 Selectedcompositionofthemicroemulsionsystems

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2910ataflowof5volH2inArinarangeoftemperaturesfrom30degC to 930degC (heating rate 10degCmin) The H2 consumptionwas monitored during the study by the difference in thermalconductivity between the inlet and outlet gases The degreeof reduction (DOR ) was calculated using H2-TPR of the in-situ reducedcatalysts015gof the freshcatalystwasreducedat 350degC (1degCmin) for 16 h in flowing H2 then flushed withheliumgas for30minAfterwards theheliumwaschanged to5 volH2 inAr and the temperaturewas increased from350to 930degC (10degCmin) and the H2 consumption was monitoredThe TCD was calibrated with Ag2O as standard The DOR wascalculated assuming that unreduced cobalt after the reductionpre-treatmentwasintheformofCo2+accordingto

1 ATCD fDORXCo AWCo

times= minus

divide

whereATCD is the integrationof theTCDsignalnormalizedpermasscatalystAWCoistheatomicweightofCo(589gmol)fisacalibrationfactorcorrelatingtheareaoftheTCDsignalandtheH2 consumedXCoisthecobaltloading(12Co)

Thecobaltdispersion(D)andthecobaltcrystallitesize(d(Codeg)nm) was calculated by hydrogen static chemisorption on thereduced catalysts The measurements were performed on aMicromeritics ASAP 202degC unit at 35degC after reducing about015gofthefreshcatalystsunderthesameconditionsasinTPRanalysis(H2flowat350degCfor16h(heatingrate1degCmin))

Themorphologyofthesupportsandfinalcatalystswasstudiedbyhighresolution-scanningelectronmicroscopy(HR-SEM)usinganXHR-SEMMagellan400instrumentsuppliedbytheFEICompanyThesampleswere investigatedusinga lowacceleratingvoltageandnoconductivecoating

Transmissionelectronmicroscopy(TEM)analysiswasperformedusingaPhilipsCM300UT-FEGelectronmicroscopewithapointresolution of 017 nm information limit of 01 nmwhichwasoperated at 200 kV in which images were acquired with aTVIPS CCD camera The samples were prepared by immersingaQuantifoilRcoppermicrogrid inafreshcatalystdispersedinethanol

Catalytic testingCO hydrogenation was tested at operating conditions similarto Fischer-Tropsch synthesis Experimentswereperformed in astainless-steelfixed-bedreactor(id9mm)atprocessconditions210degC20barmolarH2COratio=21Amixtureof1gofcatalystwith a pellet size between 53ndash90 μm was diluted and mixedwith5gofSiC(foraneventemperatureprofile)andthereafterplaced in the reactor [2832]Prior to the reaction thecatalystwasactivatedby reducing it in situwithhydrogenat350degC for16hatatmosphericpressureAfteractivation thereactorwascooleddownto180degCandthenflushedwithHebeforeincreasingthe pressure to 20 bar The catalysts were tested during twoperiodsfirstatasyngasflowof100cm3min (NTP)and in thesecond period the gas flowwas adjusted in order to obtain aCO conversion of 30 [732-34] The heavy hydrocarbons andmostof thewaterwere condensed in two traps kept at 120degCand room-temperature respectivelyTheproductgases leaving

the traps were depressurized and analyzed on-line with a gaschromatograph (GC) Agilent 6890 equipped with a thermalconductivity detector (TCD) and a flame ionization detector(FID)H2N2COCH4andCO2wereseparatedbyaCarbosieveIIpackedcolumnandanalyzedontheTCDThepercentageofCOconversionwascalculatedby

( ) 100in out

in

CO COCOconv molCOminus

= times

C1ndashC6 products were separated by an alumina-plot column andquantifiedon theFIDdetector fromwhich itwaspossibletodeterminetheC5+selectivity(SC5+)TheCO2-freeSC5+(ieSC5+ ifexcludingCO2 fromtheC-atombalance) isdefinedasfollows[2832]

SC5+=100minus(SC1+SC2+SC3+SC4)CO2free

Results and DiscussionSynthesis approachZr-Al co-precipitated in water-in-oil microemulsion Severalmicroemulsionswerepreparedinordertodefinethecompositionandtemperatureofthewatersurfactantoil (WSO)systematwhich themicroemulsionwas formedand stable The selectedweightratioinpercentageswas79264657(Table 1)TheZr-Al2O3precursorwasformedbycollisionandcoalescenceofwaterdropletsbetweenmicroemulsions1and2(ME1andME2)Oxo-hydroxocomplexesof zirconiumandaluminumwereproducedwhen the base came in contact with the metal initiating thenucleationand formationof thefirstparticles inside thewaterdroplets [1835] The simultaneous co-precipitation of theprecursors inside thewater droplets favors in thisway a gooddispersionofZrinaluminaanduniformgrowthoftheparticlesIn addition the EDX spectra of the material showed AlZrCoatomicratios(Table 2)similartotheaddedmetalsTheseresultsshowthatbothZrandAlprecipitatedduringthesynthesisandnolossofmetalwasdetected

Wetness impregnation Thecommercialaluminausedassupporthasapseudoϒ-Al2O3porousstructureThisframeworkallowsthedeposition of zirconiumfirst and after cobalt oxides inside theporesandonthesurfaceofthealuminaDuringthecalcinationstepdecompositionoftheprecursorsandreactionsbetweentheZrCoandϒ-Al2O3mightoccur

Characterization of the materialsX-Ray diffractograms The X-ray diffractograms of the carriersand Co-catalysts are illustrated in Figure 1 The Zr-Al2O3(ME)support presents a low crystalline ϒ-Al2O3 phase In addition

Material AlZr Atomic ratio AlCo Atomic ratio

Zr-Al2O3(IM) 79 -Z-Al2O3(ME) 79 -

CoZr-Al2O3(IM) 81 68CoZr-Al2O3(ME) 79 71

Table 2 RepresentativeEDXelementalanalysisofthesupportsandthecatalysts

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no Zr specieswere detectedwhichmight be attributed to theapplied synthesismethodOne explanation could be that Zr isencapsulated in the aluminamatrix and consequently Zr oxidespeciescrystalformationwasinhibited[3637]IncontrasttheZr-Al2O3(IM)materialpresentscharacteristicpeaksforϒ-Al2O3andabandat2θ=32degassignedtoametastableZrO2withorthorhombicstructure(Figure 1)

AfterCodepositiontheXRDpatterns(Figure 1 right)showedahighlycrystallineCo3O4specieswereformed inall thecatalystswithsimilarcrystallitesizesofapproximately11nm(Figure 1 and Table 3)ThusitcanbeconcludedthatthepresenceofZrdoesnotaffecttheCo3O4particlesize

N2 physisorption ThecatalystporosityispresentedinFigure 2TheisothermscorrespondtotypeIV[38]ThehysteresisloopforCoZr-Al2O3(ME)correspondstotypeH2(b)[38]associatedwithcomplexporenetworksconsistingofporeswithill-definedshapesinthemesoporerangeMaterialswithtexturalporosityformedbyvoidsbetweenparticlescanbeassociatewithtypeH2(b)Inadditionthismaterialshowednarrowporesizedistribution CoZr-Al2O3(IM)andAl2O3supportsshowedtypeH3hysteresisloop[38] correspondent tomaterialswithnon-rigidaggregatesandwideporesizedistributionlikeamorphousaluminaThecarrierisothermsweresimilar andthereforenotincludedin Figure 2

Thesurfaceareaforallmaterialswasbetween190and248m2g(Table 3) IncorporationofCoandorZrphasesonaluminaleadstoadecreaseinBETsurfaceareaandporevolume(Table 3)duetopartialporeblockageofthedepositedoxidesinsidethepores[3940]TheCo3O4particlesizewassmallerthantheAl2O3 andZr-Al2O3(IM)poresizethereforeCo3O4depositionisfavoredinsidethe pores On the other hand Zr-Al2O3(ME) had smaller porediameter sizes than the Co3O4 particles (Table 3) which leadstotheconclusionthatsomeoftheCo3O4wasdepositedonthecarriersurface

Scanning and transmission electron microscopy The Zr-Al2O3(ME) and CoZr-Al2O3(ME)morphology (Figure 3) showednon-agglomerateduniformparticlesizedistributionHoweverCoAl2O3 Zr-Al2O3(IM) and CoZr-Al2O3(IM) showed heterogeneoussphericalagglomerationsofsmallerparticlesof12080and80μmrespectivelyTheseagglomerationsareattributedtoZrandorCodepositionZr-Al2O3(ME)doesnotagglomerateaftercobaltdeposition (Figure 3) Basedon thesefindings it is consideredthat Zr prevents particle agglomeration especially when Zr ishighlydispersed

For a better understanding of the species and morphology inthe promoted-catalysts TEM pictures were taken (Figure 4)

2θ (deg)

Figure 1 X-raydiffractogramsofthecarriers(left)calcinedat500degCfor6handcobalt-catalysts(right)calcinedat350degCfor10h

Sample

N2 Physisorption XRD Chemisorption TPRBET

Surface area (m2g)

Total Pore volumea

(cm3g)

Average Pore diameter

(nm) b

Particle size Co3O4 (nm) c

Particle size

Co0 (nm) dParticle size Co0 (nm) e

Metal Dispersion D f DOR i

Al2O3 283 11 147 - - - - -Zr-Al2O3 (IM) 239 08 140 - - - - -Zr-Al2O3(ME) 211 03 65 - - - - -CoAl2O3 248 09 140 105 79 26 45 30

CoZr-Al2O3(IM) 227 07 127 113 85 27 80 47CoZrAl2O3(ME) 191 03 58 113 85 41 70 11

Table 3Physicochemicalcharacterizationofthesupportsandcatalysts aDeterminedfromasinglepointofadsorptionatPP0=0998bEstimated

byBJHformalism(adsorptionbranch)cAveragecrystallitesizeofCo3O4estimatedfromScherrerequationdAccordingwithd(Co0)=075d(Co3O4)

eAccordingtod(Co0)H fMetaldispersionafterreductionat350degCfor16hinH2iDegreofreduction(DOR)fromTPRofreducedcatalysts

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H2-Temperature programmed reduction A typical TPR profileforallthecatalystsisshowninFigure 5IngeneralthefirsttwopeakscorrespondtothereductionofCo3O4+H2rarr3CoO+H2O [41]and3CoO+3H2rarr3Co0+3H2O[42]Thepeakaround700degCis attributed toCo3AlO6 (Co3O4-AlO2) andorCoO-Al2O3and thepeakat900degCcorrespondstoCoAl2O4[43-45]

Co3O4 in CoZr-Al2O3(ME) was harder to reduce as aconsequence the reduction temperature was shifted towardshigher temperature compared to the other catalysts The lackof crystallinity in the ME carrier favored the cobalt-aluminateformationandalsoitsreductiontemperature

TheTPRforCoZr-Al2O3(IM)presentssimilarpeaksasforCoAl2O3 withthedifferencethatthereductiontemperaturewaslowerbyabout 50degC In addition an extra H2 uptakewas seen at 608degCwhichcancorrespondtothepartialreductionofZrTheamountof cobalt aluminate specieswasdecreasedcomparedwithCoAl2O3attributedtothepresenceofZrCoAl2O4(spinel)wasnotdetected by the XRD technique since its diffractogram peaksoverlapstheCo3O4peaks

Additionally TPR experiments (Figure 5 right)were performedafter the catalyst activation in order to identify the unreducedcobalt amount and consequently the degree of reduction(DOR) (ie from 350 to 930degC in H2) Co3O4 in CoZr-Al2O3(IM)iscompletelyreducedaftercatalystactivationwithaDORof47whiletheDORforCoAl2O3andforZr-Al2O3(ME)is30and11 respectively (Table 3 and Figure 5) Thereafter it can beconcludedthatthepresenceofZrinislandsasisthecaseofCoZr-Al2O3(IM)decreasethecobalt-aluminainteractionsfavoringinthisway amoremetallic formationwhich is required for a COhydrogenationreaction

Interestingtonoteinallthecatalysts(Figure 5 right)isthattheunreducedcobaltspecies(peaksaround700and900degC)shiftedthe reduction temperature to higher temperatures comparedwiththefirstTPRanalysis(Figure 5 left)Theexplanationgivenisthatduringcatalystsactivationtheremainingunreduced-cobaltintheformofCodeg interactswithwater(producedbythemetalreduction) to form Co-aluminate which is reduced at a highertemperature[15]

Table 3 presentsthedispersionofmetalliccobaltCodegcalculatedbyH2chemisorption(illustratedinexperimentalpart)TheresultsshowthatCodegdispersionisquitesimilar inCoZr-Al2O3(IM) andCoZr-Al2O3(ME) These results compared with CoAl2O3 arehighersoit isconcludedthatZrfavorsthedispersionofcobaltinaluminasupportInadditionthemeasuredCodegparticlesizebythistechniqueandbyTEMishigherthanthecalculatedfromtheScherrerequation fromwhich it canbeconcluded thatduringcatalystactivationthemetallicparticlesaresinteredThiseffectishigher inCoZr-Al2O3(ME)andoneof theexplanationsmightbeduetothetexturalporosityandthelackofstructuralporositywhichmakesthecobalt-sinteringeasier

Catalytic testComparingCOconversionsforallthecatalystsafter25hofsyngasstream(H2 CO=21)(Table 4)thecatalystactivitydecreasesinthefollowingorderCoZr-Al2O3(IM)gtCoAl2O3gtCoZr-Al2O3(ME)The

00 02 04 06 08 10

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Pore diameter [nm]

Figure 2 TheN2 adsorption-desorption isotherms and pore sizedistributioncurvesforthecobaltcatalysts

CoZr-Al2O3(ME) shows a homogeneous material formed byagglomerated nanoparticles CoZr-Al2O3(ME) shows carrierparticlesizesbetween4-7nmandCo3O4cubiccrystals(Figure 4a)STEM-EDXmappingresultsshowahomogeneousdistributionofZronCoZr-Al2O3(ME) (Figure 4a)ThispicturedemonstrateshowtheMEtechniquecanbeappliedforthesynthesisofhighlydisperseoxidepromoteronacarrierTheZrdispersiononaluminainCoZr-Al2O3(IM)(Figure 4b)waslowerformingZr-richislandsontheAl2O3 surfaceFurthermorethecobaltdepositionseemstobebetterintheMEmaterialthanintheZr-impregnatedmaterial

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Figure 3 SEMpicturesforthecarrierandthecobaltcatalysts

a)CoZr-Al2O3(ME) b) CoZr-Al2O3(IM )

20 nm 300 nm

600 nm

Zr Zr

Al Co Co Al

300 nm

4 nm

Figure 4 RepresentativeSTEM-EDXelementalmappingfora)CoZr-Al2O3(ME)andb)CoZr-Al2O3(IM)

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resultsarerelatedtothehighertheDOR(degreeofreductionofCo)thehighertheCOconversioninperiodone(Table 3)

InallthecasestheselectivityisaffectedbytheCOconversionthe higher the CO conversion the higher the C5+ selectivity(SC5+)andasaconsequencetheselectivitytoCH4andC2-C4aredecreasedTheselectivity toCH4andC2-C4werehigher for theMEcatalystduringbothperiodsthismightbeattributedtotwofactslowCo0formationintheCoZr-Al2O3 (ME)catalystandthesmallpore sizeof thecarrier around4nm leading to internalmasstransferlimitationsfavoringthefasterH2 diffusionduetoitssmallersizecomparedtotheCOmoleculewhichdiffusesmoreslowlyThisledtohigherH2COratioswithinthecatalystparticlesthanatthepelletsurface

ConclusionForthefirsttimeZr-Aloxidesnanoparticlesweresynthesizedbythewater-in-oilmicroemulsionmethodThematerialpresentedahighZrdispersioninaluminaanditwashighlyhomogeneouswith uniform particle size narrow pore size distribution andhighsurfaceareaThismaterialwasusedascobaltsupportandcomparedwithsimilarmaterialpreparedbyZr impregnatedoncommercial alumina The presence of ZrO2-islands on aluminafavoredthedispersionanddegreeofreductionofcobaltwhile

the high Zr dispersion in the Zr-Al2O3 (ME) material hinderedZrO2crystallizationThisproducedamoreamorphousmaterialleading to ahigherdegreeof CoAl2O4 formationand thereforeincreased selectivity tomethaneand short-chainhydrocarbonsC2-C4ThecatalyticactivityandSC5+isfavouredbytheCoZr-Al2O3

(IM)catalystTheseresultsareattributedtothecatalystporosityandhigherCo0availabilityonthesurfaceHowevereven if thecobaltonZr-Al2O3nanoparticles(preparedbywater-in-oilmicroemulsion)isnotthebestcatalystforCOhydrogenationreactionwhen a high C5+ selectivity is desired the material has verygoodpropertiestobeconsideredforotherapplicationssuchasbasedmaterial in three-way-catalyst or as catalyst support forothercatalyticreactionlikehydrodesulphurizationortostabilizealuminaphaseswhenitisusedathightemperatures

Acknowledgments SwedishInternationalDevelopmentCooperationAgency(SIDA)NanoandesnetworkandEuropeanprojectCOSTActionCM1101forfinancialsupportSpecialthankstoDrEmanuelaNegro(DeftUniversityofTechnology)EdgarCardenas(LulearingUniversity)andCesarLeyvaPorras(CIMAVSC)formeasurementsofTEMSEMandHRTEMSTEM

0 200 400 600 800 1000 1200

804CoZr-Al2O3(ME)

CoZr-Al2O3(IM)

722

466

918

742608

350

252

925734

383

318CoAl2O3

Inte

nsity

(au

)

Temperature [degC]400 600 800 1000 1200

968754

428

989749

625

838744

606

CoAl2O3

CoZr-Al2O3 (IM)

CoZr-Al2O3 (ME)

Inte

nsity

(au

)

Temperature [degC]

Figure 5 TPRprofileforthefreshcatalyst(left)andafteractivationat350degCfor16h(right)

GHSV (Ncm3(gh-1) Catalysts XCO () SCH4a

() SC2-C4a () SC5+

a () SCO2 ()

6000 CoAl2O3 65 120 120 750 101500 CoAl2O3 280 85 110 800 056000 CoZr-Al2O3(IM) 120 100 78 810 122350 CoZr-Al2O3(IM) 310 76 60 860 046000 CoZr-Al2O3(ME) 40 200 160 610 301000 CoZr-Al2O3(ME) 270 170 150 670 10

Table 4COconversionlevelsandselectivitydataforthedifferentcatalystsa SelectivitiesareCO2-free

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9 MiyazawaTHanaokaTShimuraKHirataS(2014)FischerndashTropschsynthesis over aCoSiO2 catalystmodifiedwithMn- andZrunderpracticalconditionsCatalCommun5736-39

10 Miyazawa T Hanaoka T Shimura K Hirata S (2013) Mn and Zrmodified CoSiO2 catalysts development in slurry-phase FischerndashTropschsynthesisAppliedCatalysisAGeneral46747-54

11 LiuYChenJFangKWangYSunY(2007)Alargepore-sizemesoporouszirconiasupportedcobaltcatalystwithgoodperformanceinFischerndashTropschsynthesisCatalCommun8945-949

12 Li ZWu J Yu JHanDWuL et al (2016)Effectof incorporationmanner of Zr on the CoSBA-15 catalyst for the FischerndashTropschsynthesisJMolCatalAChem424384-392

13 ShimuraKMiyazawaTHanaokaTHirataS(2015)FischerndashTropschsynthesisoveraluminasupportedcobaltcatalystEffectofpromoteradditionAppliedCatalysisAGeneral4941-11

14 Enache DI Roy-Auberger M Revel R (2014) Differences in thecharacteristics and catalytic properties of cobalt-based FischerndashTropsch catalysts supported on zirconia and alumina AppliedCatalysisAGeneral26851-60

15 RohrF LindvaringgOAHolmenABlekkanEA (2000)FischerndashTropschsynthesis over cobalt catalysts supported on zirconia-modifiedaluminaCatalToday58247-254

16 Jongsomjit B Panpranot J Goodwin JG (2003) Effect of zirconia-modifiedaluminaonthepropertiesofCoγ-Al2O3catalysts JCatal21566-77

17 Jacobs G Das TK Zhang Y Li J Racoillet G et al (2002) FischerndashTropsch synthesis support loading and promoter effects on thereducibility of cobalt catalysts Applied Catalysis A General 233263-281

18 Boutonnet M Marinas A Montes V Suaacuterez-Paris R Saacutenchez-Domınguez M (2016) Nanocatalysts Synthesis in Nanostructured

Liquid Media and Their Application in Energy and Production ofChemicalsinNanocolloidsElsevierAmsterdampp211-246

19 KombaiahKVijayaJJKennedyLJBououdinaMAl-LohedanHAetal(2017)StudiesonOpuntiadileniihawmediatedmultifunctionalZnFe2O4nanoparticlesOpticalmagneticandcatalyticapplicationsMaterChemPhys194153-164

20 Singh AK (2016) Structure Synthesis and Application ofNanoparticlesinEngineeredNanoparticlesAcademicPressBostonpp19-76

21 Eriksson S Nyleacuten U Rojas S Boutonnet M (2004) Preparationof catalysts from microemulsions and their applications inheterogeneouscatalysisApplCatalA265207-219

22 Pardo-Tarifa F Cabrera S Sanchez-Dominguez M Boutonnet M(2017) Ce-promoted CoAl 2 O 3 catalysts for Fischer-TropschsynthesisIntJHydrogenEnergy429754-9765

23 BoutonnetMSanchez-DominguezM(2017)MicroemulsiondropletstocatalyticallyactivenanoparticlesHowtheapplicationofcolloidaltools in catalysis aims towell design and efficient catalysts CatalToday28589-103

24 MisonoM(2013)ChemistryandCatalysisofMixedOxidesStudSurfSciCatal25-65

25 Sprague MJ (1985) Characterization of heterogeneous catalystsChemieIngenieurTechnik57430-430

26 LemaitreJLDelannayPGF(1984)CharacterizationofHeterogeneousCatalystsDenkerNewYork299-365

27 Schanke D Vada S Blekkan EA Hilmen AM Hoff A et al (1995)StudyofPt-promotedcobaltCOhydrogenationcatalystsJCatal15685-95

28 LoumlgdbergSLualdiMJaumlraringsSWalmsleyJCBlekkanEAetal(2010)Ontheselectivityofcobalt-basedFischerndashTropschcatalystsevidenceforacommonprecursorformethaneandlong-chainhydrocarbonsJCatal27484-98

29 ReuelRCBartholomewCH(1984)ThestoichiometriesofH2andCOadsorptionsoncobaltEffectsofsupportandpreparationJCatal8563-77

30 Jones RD Bartholomew CH (1988) Improved flow technique formeasurementofhydrogen chemisorptiononmetal catalystsApplCatal3977-88

31 Bhatia S Beltramini J Do DD (1990) Temperature programmedanalysisanditsapplicationsincatalyticsystemsCatalToday7309-438

32 Lualdi M Loumlgdberg S Regali F Boutonnet M Jaumlrarings S (2011)Investigation of mixtures of a Co-based catalyst and a Cu-basedcatalyst for the FischerndashTropsch synthesis with bio-syngas theimportanceofindigenouswaterTopCatal54977-985

33 Storsaeligter S Borg Oslash Blekkan EA Holmen A (2005) Study of theeffectofwateronFischerndashTropschsynthesisoversupportedcobaltcatalystsJCatal231405-419

34 Lualdi M (2012) Fischer-Tropsch Synthesis over Cobalt-basedCatalystsforBTLApplications

35 BoutonnetMLoumlgdbergSSvenssonEE(2008)RecentdevelopmentsintheapplicationofnanoparticlespreparedfromwomicroemulsionsinheterogeneouscatalysisCurrOpinColloidInterfaceSci13270-286

36 ChandradassJKimKH(2009)Effectofacidityonthecitrate-nitrate

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combustion synthesis of alumina-zirconia composite powderMetMaterInt151039-1043

37 Baudiacuten C (2014) Processing of Alumina and CorrespondingCompositesComprehensiveHardMaterials3172

38 ThommesMKanekoKNeimarkAVOlivier JP Rodriguez-ReinosoFetal(2015)Physisorptionofgaseswithspecialreferencetotheevaluation of surface area and pore size distribution Pure ApplChem871051-1069

39 MartiacutenezAPrietoGRollaacutenJ(2009)Nanofibrousγ-Al2O3assupportforCo-basedFischerndashTropschcatalystsponderingtherelevanceofdiffusionalanddispersioneffectsoncatalyticperformance JCatal263292-305

40 Liu C Li J Zhang Y Chen S Zhu J et al (2012) FischerndashTropschsynthesisovercobaltcatalystssupportedonnanostructuredaluminawithvariousmorphologiesJMolCatalAChem363335-342

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42 OslashyvindBMagnusRSOslashlviSAndersH(2007)Identificationofcobaltspecies during temperature programmed reduction of Fischer-TropschcatalystsStudiesinSurfaceScienceandCatalysis163255-272

43 Topsoslashe NY Topsoslashe H (1982) Adsorption studies onhydrodesulfurization catalysts I Infrared and volumetric study ofNOadsorptiononalumina-supportedCoMoandCo-MocatalystsintheircalcinedstateJCatal75354-374

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Page 2: Synthesis and Characterization of Novel Zr-Al2O3 ... Prepared2 by Microemulsion Method and Its Use as Cobalt Catalyst Support for the CO Hydrogenation Reaction. Synth Catal. 2017,

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to the increaseofactive intermediates (-CH2-)whichcausesanenhancementofthecatalystactivityandtheselectivitytolong-chainhydrocarbons[15]OtherauthorsfoundthatZrenhancesthe cobalt reducibility and consequently the catalyst activity[131617]OntheotherhandasimportantasthechoiceofthepromoteristhechoiceofthesynthesismethodConsideringtherelevance of the synthesis procedure for obtaining promotedalumina supports themicroemulsion preparationmethod is apromisingstrategyItallowsthesynthesisofhighlyhomogeneousmaterialswithcontrolledstructuralpropertiesandparticlesizes[18] Thismethodology has been employed for preparation ofmetal nanoparticles metal oxides andmixedmetal oxides forcatalytic and electrochemical processes [1920] The synthesisof inorganic nanoparticles in water-in-oil microemulsionsis driven by microscopic micelles that act as nanoreactorswhere the nanoparticle synthesis occurs A water-in-oil (WO)microemulsion isatransparentortranslucentsolutionwhich isopticallyisotropicandthermodynamicallystableItismadeupofdropletsofwatersurroundedbyacontinuousoilphasewheretheinterfacialtensionbetweenoilandwaterisovercomebytheuseofsurfactants[1821]

Thesynthesisofavarietyofbinarymetaloxideshasbeenstudiedascatalystssupportsforseveralcatalyticreactionsandhasshowngood results due to a high homogeneity and intimate binarymetal interaction Inadditionsmallsizeparticlesmaximizethesurfaceareaexposedtothereactantallowingmorereactionstooccur[2223]

BasedonthepresentedliteraturethepresenceofZrinaluminaincreasestheCOhydrogenationreactionhoweverthemethodof Zr incorporation intoAl2O3 has not been fully investigatedIn addition binary oxide nanoparticles used as supports havegiven good results in different application [24] To the bestof our knowledge no Zr-Al nanoparticles co-precipitated bymicroemulsion method have previously been prepared andstudied Therefore the synthesis of Zr-Al oxidenanoparticles isan adequate candidate for preparing cobalt catalyst supportsThe aim of thiswork is to synthesized aswell as to study thecharacteristicsofco-precipitatedZr-AlnanoparticlesAtthesametimeunderstandhowaffectthismaterialcomparedwithsimilaronesonthecobaltdepositionandfurtherapplicationascatalystforCOhydrogenationreaction

ExperimentalCatalyst preparationTheco-precipitationofZr-Alnanoparticleswasaccomplishedbymixingtwowater-in-oilmicroemulsionsolutions(microemulsion1(ME1)andmicroemulsion2(ME2))forcomposition(Table 1)ME1 contained Zr and Al precursors whileME2 contained theprecipitating agent NH4OH ME2 was added to ME1 dropwiseunder continuous stirring at 30degC until pH 9was reached Thesolutionwaskeptatconstantconditionsfor12htocompletethereaction The final solutionwas destabilizedwith acetone andthe solidproductwas separatedby centrifugationandwashedwithacetoneandwaterTheproductwas freeze-dried inorderto avoid the particles agglomeration Afterwards the productwascalcinedinairfor6hat550degC(heatingrate10degCmin)TheobtainedmaterialwaslabeledasZr-Al2O3 (ME)

For comparison Al2O3 and ZrAl2O3 were also prepared Acommercial pseudo-boehmite Al2O3 (Versal 250) was driedat 120degC for 5 h and calcined at 550degC for 6 h Afterwards anaqueous solutionofZrO(NO3)2waspreparedandadded to thetreatedaluminabyincipientwetnessimpregnation(molarratioAlZr=8)ThematerialwasthermallytreatedinthesamewayasZr-Al2O3(ME) TheobtainedmaterialwaslabeledasZr-Al2O3(IM)

Thecarriers(Zr-Al2O3 (ME)Zr-Al2O3(IM)andAl2O3)weredriedat120degCfor5hpriortothe12wtofcobaltdepositionAnaqueoussolution of Co(NO3)2middot6H2Owith volume equivalent to the porevolumeofeachsupportwasaddedtothesupportsdropwiseThecarrierporevolumewasdeterminedbyN2-adsorptiontechniqueAftermetal impregnation thematerials were dried for 6 h at120degC and calcined in air at 350degC for 10h (heating rate 1degCmin)ThefinalcatalystswerelabeledasCoZr-Al2O3(ME)CoZr-Al2O3(IM)andCoAl2O3

Catalyst characterizationX-raydiffraction (XRD) of the fresh sampleswas performedonaSiemensD5000X-raydiffractometerwithCuKαradiation(40kV30mA)Themeasurementswererecorded from10deg to90degin the 2θ range using a step size of 0020deg and a steptimeof12s for all the samples Thephaseswere identifiedby theEvasoftware(version130022007)CrystallitesizesofCo3O4werecalculated using the Scherrer equation and assuming sphericalparticles[25]TheCodegcrystallitesizewasestimatedfromCo3O4 using the formula d(Codeg)=075d(Co3O4) [2627] The analyseswere performed in a pressure interval between 20 and 510mm Hg Chemisorption isotherms were extrapolated at zeropressure in order to determine the adsorption of hydrogen[28] The stoichiometry assumptionwas that two cobalt atompermoleculeofhydrogenTheaverageparticlesizeofCodegwasestimatedaccordingtod(Codeg)H=96DmiddotDORassumingsphericalshape[2930]

BrunauerndashEmmetndashTeller (BET) surface area and porosity datawascollectedwithaMicromeriticsASAP20002020unit02gofthesampleswasoutgassedat250degCovernightpriortoanalysisThe data was recorded by N2 adsorption at liquid nitrogentemperatureatrelativepressuresbetween006and02

The reducibility of the catalysts was investigated by hydrogentemperature-programmedreduction(H2-TPR)[31]Thecalcinedcatalysts (015 g) were studied in a Micromeritics Autochem

ME Phase Compound(s) Composition (wt )

ME1

Oil Hexane 657Surfactant Brijcopy 264AqueousSolution

1M(AlCl36H2O-ZrO(NO3)2)molarratioofZrAl=18) 79

ME2

Oil Hexane 657Surfactant Brijcopy 264Aqueoussolution NH4OH38wt 79

Table 1 Selectedcompositionofthemicroemulsionsystems

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2910ataflowof5volH2inArinarangeoftemperaturesfrom30degC to 930degC (heating rate 10degCmin) The H2 consumptionwas monitored during the study by the difference in thermalconductivity between the inlet and outlet gases The degreeof reduction (DOR ) was calculated using H2-TPR of the in-situ reducedcatalysts015gof the freshcatalystwasreducedat 350degC (1degCmin) for 16 h in flowing H2 then flushed withheliumgas for30minAfterwards theheliumwaschanged to5 volH2 inAr and the temperaturewas increased from350to 930degC (10degCmin) and the H2 consumption was monitoredThe TCD was calibrated with Ag2O as standard The DOR wascalculated assuming that unreduced cobalt after the reductionpre-treatmentwasintheformofCo2+accordingto

1 ATCD fDORXCo AWCo

times= minus

divide

whereATCD is the integrationof theTCDsignalnormalizedpermasscatalystAWCoistheatomicweightofCo(589gmol)fisacalibrationfactorcorrelatingtheareaoftheTCDsignalandtheH2 consumedXCoisthecobaltloading(12Co)

Thecobaltdispersion(D)andthecobaltcrystallitesize(d(Codeg)nm) was calculated by hydrogen static chemisorption on thereduced catalysts The measurements were performed on aMicromeritics ASAP 202degC unit at 35degC after reducing about015gofthefreshcatalystsunderthesameconditionsasinTPRanalysis(H2flowat350degCfor16h(heatingrate1degCmin))

Themorphologyofthesupportsandfinalcatalystswasstudiedbyhighresolution-scanningelectronmicroscopy(HR-SEM)usinganXHR-SEMMagellan400instrumentsuppliedbytheFEICompanyThesampleswere investigatedusinga lowacceleratingvoltageandnoconductivecoating

Transmissionelectronmicroscopy(TEM)analysiswasperformedusingaPhilipsCM300UT-FEGelectronmicroscopewithapointresolution of 017 nm information limit of 01 nmwhichwasoperated at 200 kV in which images were acquired with aTVIPS CCD camera The samples were prepared by immersingaQuantifoilRcoppermicrogrid inafreshcatalystdispersedinethanol

Catalytic testingCO hydrogenation was tested at operating conditions similarto Fischer-Tropsch synthesis Experimentswereperformed in astainless-steelfixed-bedreactor(id9mm)atprocessconditions210degC20barmolarH2COratio=21Amixtureof1gofcatalystwith a pellet size between 53ndash90 μm was diluted and mixedwith5gofSiC(foraneventemperatureprofile)andthereafterplaced in the reactor [2832]Prior to the reaction thecatalystwasactivatedby reducing it in situwithhydrogenat350degC for16hatatmosphericpressureAfteractivation thereactorwascooleddownto180degCandthenflushedwithHebeforeincreasingthe pressure to 20 bar The catalysts were tested during twoperiodsfirstatasyngasflowof100cm3min (NTP)and in thesecond period the gas flowwas adjusted in order to obtain aCO conversion of 30 [732-34] The heavy hydrocarbons andmostof thewaterwere condensed in two traps kept at 120degCand room-temperature respectivelyTheproductgases leaving

the traps were depressurized and analyzed on-line with a gaschromatograph (GC) Agilent 6890 equipped with a thermalconductivity detector (TCD) and a flame ionization detector(FID)H2N2COCH4andCO2wereseparatedbyaCarbosieveIIpackedcolumnandanalyzedontheTCDThepercentageofCOconversionwascalculatedby

( ) 100in out

in

CO COCOconv molCOminus

= times

C1ndashC6 products were separated by an alumina-plot column andquantifiedon theFIDdetector fromwhich itwaspossibletodeterminetheC5+selectivity(SC5+)TheCO2-freeSC5+(ieSC5+ ifexcludingCO2 fromtheC-atombalance) isdefinedasfollows[2832]

SC5+=100minus(SC1+SC2+SC3+SC4)CO2free

Results and DiscussionSynthesis approachZr-Al co-precipitated in water-in-oil microemulsion Severalmicroemulsionswerepreparedinordertodefinethecompositionandtemperatureofthewatersurfactantoil (WSO)systematwhich themicroemulsionwas formedand stable The selectedweightratioinpercentageswas79264657(Table 1)TheZr-Al2O3precursorwasformedbycollisionandcoalescenceofwaterdropletsbetweenmicroemulsions1and2(ME1andME2)Oxo-hydroxocomplexesof zirconiumandaluminumwereproducedwhen the base came in contact with the metal initiating thenucleationand formationof thefirstparticles inside thewaterdroplets [1835] The simultaneous co-precipitation of theprecursors inside thewater droplets favors in thisway a gooddispersionofZrinaluminaanduniformgrowthoftheparticlesIn addition the EDX spectra of the material showed AlZrCoatomicratios(Table 2)similartotheaddedmetalsTheseresultsshowthatbothZrandAlprecipitatedduringthesynthesisandnolossofmetalwasdetected

Wetness impregnation Thecommercialaluminausedassupporthasapseudoϒ-Al2O3porousstructureThisframeworkallowsthedeposition of zirconiumfirst and after cobalt oxides inside theporesandonthesurfaceofthealuminaDuringthecalcinationstepdecompositionoftheprecursorsandreactionsbetweentheZrCoandϒ-Al2O3mightoccur

Characterization of the materialsX-Ray diffractograms The X-ray diffractograms of the carriersand Co-catalysts are illustrated in Figure 1 The Zr-Al2O3(ME)support presents a low crystalline ϒ-Al2O3 phase In addition

Material AlZr Atomic ratio AlCo Atomic ratio

Zr-Al2O3(IM) 79 -Z-Al2O3(ME) 79 -

CoZr-Al2O3(IM) 81 68CoZr-Al2O3(ME) 79 71

Table 2 RepresentativeEDXelementalanalysisofthesupportsandthecatalysts

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no Zr specieswere detectedwhichmight be attributed to theapplied synthesismethodOne explanation could be that Zr isencapsulated in the aluminamatrix and consequently Zr oxidespeciescrystalformationwasinhibited[3637]IncontrasttheZr-Al2O3(IM)materialpresentscharacteristicpeaksforϒ-Al2O3andabandat2θ=32degassignedtoametastableZrO2withorthorhombicstructure(Figure 1)

AfterCodepositiontheXRDpatterns(Figure 1 right)showedahighlycrystallineCo3O4specieswereformed inall thecatalystswithsimilarcrystallitesizesofapproximately11nm(Figure 1 and Table 3)ThusitcanbeconcludedthatthepresenceofZrdoesnotaffecttheCo3O4particlesize

N2 physisorption ThecatalystporosityispresentedinFigure 2TheisothermscorrespondtotypeIV[38]ThehysteresisloopforCoZr-Al2O3(ME)correspondstotypeH2(b)[38]associatedwithcomplexporenetworksconsistingofporeswithill-definedshapesinthemesoporerangeMaterialswithtexturalporosityformedbyvoidsbetweenparticlescanbeassociatewithtypeH2(b)Inadditionthismaterialshowednarrowporesizedistribution CoZr-Al2O3(IM)andAl2O3supportsshowedtypeH3hysteresisloop[38] correspondent tomaterialswithnon-rigidaggregatesandwideporesizedistributionlikeamorphousaluminaThecarrierisothermsweresimilar andthereforenotincludedin Figure 2

Thesurfaceareaforallmaterialswasbetween190and248m2g(Table 3) IncorporationofCoandorZrphasesonaluminaleadstoadecreaseinBETsurfaceareaandporevolume(Table 3)duetopartialporeblockageofthedepositedoxidesinsidethepores[3940]TheCo3O4particlesizewassmallerthantheAl2O3 andZr-Al2O3(IM)poresizethereforeCo3O4depositionisfavoredinsidethe pores On the other hand Zr-Al2O3(ME) had smaller porediameter sizes than the Co3O4 particles (Table 3) which leadstotheconclusionthatsomeoftheCo3O4wasdepositedonthecarriersurface

Scanning and transmission electron microscopy The Zr-Al2O3(ME) and CoZr-Al2O3(ME)morphology (Figure 3) showednon-agglomerateduniformparticlesizedistributionHoweverCoAl2O3 Zr-Al2O3(IM) and CoZr-Al2O3(IM) showed heterogeneoussphericalagglomerationsofsmallerparticlesof12080and80μmrespectivelyTheseagglomerationsareattributedtoZrandorCodepositionZr-Al2O3(ME)doesnotagglomerateaftercobaltdeposition (Figure 3) Basedon thesefindings it is consideredthat Zr prevents particle agglomeration especially when Zr ishighlydispersed

For a better understanding of the species and morphology inthe promoted-catalysts TEM pictures were taken (Figure 4)

2θ (deg)

Figure 1 X-raydiffractogramsofthecarriers(left)calcinedat500degCfor6handcobalt-catalysts(right)calcinedat350degCfor10h

Sample

N2 Physisorption XRD Chemisorption TPRBET

Surface area (m2g)

Total Pore volumea

(cm3g)

Average Pore diameter

(nm) b

Particle size Co3O4 (nm) c

Particle size

Co0 (nm) dParticle size Co0 (nm) e

Metal Dispersion D f DOR i

Al2O3 283 11 147 - - - - -Zr-Al2O3 (IM) 239 08 140 - - - - -Zr-Al2O3(ME) 211 03 65 - - - - -CoAl2O3 248 09 140 105 79 26 45 30

CoZr-Al2O3(IM) 227 07 127 113 85 27 80 47CoZrAl2O3(ME) 191 03 58 113 85 41 70 11

Table 3Physicochemicalcharacterizationofthesupportsandcatalysts aDeterminedfromasinglepointofadsorptionatPP0=0998bEstimated

byBJHformalism(adsorptionbranch)cAveragecrystallitesizeofCo3O4estimatedfromScherrerequationdAccordingwithd(Co0)=075d(Co3O4)

eAccordingtod(Co0)H fMetaldispersionafterreductionat350degCfor16hinH2iDegreofreduction(DOR)fromTPRofreducedcatalysts

5

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H2-Temperature programmed reduction A typical TPR profileforallthecatalystsisshowninFigure 5IngeneralthefirsttwopeakscorrespondtothereductionofCo3O4+H2rarr3CoO+H2O [41]and3CoO+3H2rarr3Co0+3H2O[42]Thepeakaround700degCis attributed toCo3AlO6 (Co3O4-AlO2) andorCoO-Al2O3and thepeakat900degCcorrespondstoCoAl2O4[43-45]

Co3O4 in CoZr-Al2O3(ME) was harder to reduce as aconsequence the reduction temperature was shifted towardshigher temperature compared to the other catalysts The lackof crystallinity in the ME carrier favored the cobalt-aluminateformationandalsoitsreductiontemperature

TheTPRforCoZr-Al2O3(IM)presentssimilarpeaksasforCoAl2O3 withthedifferencethatthereductiontemperaturewaslowerbyabout 50degC In addition an extra H2 uptakewas seen at 608degCwhichcancorrespondtothepartialreductionofZrTheamountof cobalt aluminate specieswasdecreasedcomparedwithCoAl2O3attributedtothepresenceofZrCoAl2O4(spinel)wasnotdetected by the XRD technique since its diffractogram peaksoverlapstheCo3O4peaks

Additionally TPR experiments (Figure 5 right)were performedafter the catalyst activation in order to identify the unreducedcobalt amount and consequently the degree of reduction(DOR) (ie from 350 to 930degC in H2) Co3O4 in CoZr-Al2O3(IM)iscompletelyreducedaftercatalystactivationwithaDORof47whiletheDORforCoAl2O3andforZr-Al2O3(ME)is30and11 respectively (Table 3 and Figure 5) Thereafter it can beconcludedthatthepresenceofZrinislandsasisthecaseofCoZr-Al2O3(IM)decreasethecobalt-aluminainteractionsfavoringinthisway amoremetallic formationwhich is required for a COhydrogenationreaction

Interestingtonoteinallthecatalysts(Figure 5 right)isthattheunreducedcobaltspecies(peaksaround700and900degC)shiftedthe reduction temperature to higher temperatures comparedwiththefirstTPRanalysis(Figure 5 left)Theexplanationgivenisthatduringcatalystsactivationtheremainingunreduced-cobaltintheformofCodeg interactswithwater(producedbythemetalreduction) to form Co-aluminate which is reduced at a highertemperature[15]

Table 3 presentsthedispersionofmetalliccobaltCodegcalculatedbyH2chemisorption(illustratedinexperimentalpart)TheresultsshowthatCodegdispersionisquitesimilar inCoZr-Al2O3(IM) andCoZr-Al2O3(ME) These results compared with CoAl2O3 arehighersoit isconcludedthatZrfavorsthedispersionofcobaltinaluminasupportInadditionthemeasuredCodegparticlesizebythistechniqueandbyTEMishigherthanthecalculatedfromtheScherrerequation fromwhich it canbeconcluded thatduringcatalystactivationthemetallicparticlesaresinteredThiseffectishigher inCoZr-Al2O3(ME)andoneof theexplanationsmightbeduetothetexturalporosityandthelackofstructuralporositywhichmakesthecobalt-sinteringeasier

Catalytic testComparingCOconversionsforallthecatalystsafter25hofsyngasstream(H2 CO=21)(Table 4)thecatalystactivitydecreasesinthefollowingorderCoZr-Al2O3(IM)gtCoAl2O3gtCoZr-Al2O3(ME)The

00 02 04 06 08 10

100

200

300

400

500

Volum

e ad

sorb

ed [c

m3 g

STP

]

Relative Pressure (PP0)

CoZr-Al2O3(IM)

0 20 40 60 80 100 120 140 160

000

002

004

006

008

010

012

Pore

vol

ume

volu

me

[cm

3 g]

Pore diameter [nm]

00 02 04 06 08 10

100

200

300

400

500

600

Relative Pressure (PP0)

CoAl2O3

Volum

e ad

sorb

ed [c

m3 g

STP

]

0 20 40 60 80 100 120 140 160

000

002

004

006

008

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012

Pore diameter [nm]

Pore

volum

e volu

me [c

m3 g]

-04 -02 00 02 04 06 08 10

50

100

150

200

250

CoZr-Al2O3(ME)

Relative Pressure (PP0)

Volum

e ad

sorb

ed [c

m3 g

STP

]

0 5 10 15 20

000

002

004

006

008

010

012

Pore

volu

me v

olum

e [cm

3 g]

Pore diameter [nm]

Figure 2 TheN2 adsorption-desorption isotherms and pore sizedistributioncurvesforthecobaltcatalysts

CoZr-Al2O3(ME) shows a homogeneous material formed byagglomerated nanoparticles CoZr-Al2O3(ME) shows carrierparticlesizesbetween4-7nmandCo3O4cubiccrystals(Figure 4a)STEM-EDXmappingresultsshowahomogeneousdistributionofZronCoZr-Al2O3(ME) (Figure 4a)ThispicturedemonstrateshowtheMEtechniquecanbeappliedforthesynthesisofhighlydisperseoxidepromoteronacarrierTheZrdispersiononaluminainCoZr-Al2O3(IM)(Figure 4b)waslowerformingZr-richislandsontheAl2O3 surfaceFurthermorethecobaltdepositionseemstobebetterintheMEmaterialthanintheZr-impregnatedmaterial

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Figure 3 SEMpicturesforthecarrierandthecobaltcatalysts

a)CoZr-Al2O3(ME) b) CoZr-Al2O3(IM )

20 nm 300 nm

600 nm

Zr Zr

Al Co Co Al

300 nm

4 nm

Figure 4 RepresentativeSTEM-EDXelementalmappingfora)CoZr-Al2O3(ME)andb)CoZr-Al2O3(IM)

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resultsarerelatedtothehighertheDOR(degreeofreductionofCo)thehighertheCOconversioninperiodone(Table 3)

InallthecasestheselectivityisaffectedbytheCOconversionthe higher the CO conversion the higher the C5+ selectivity(SC5+)andasaconsequencetheselectivitytoCH4andC2-C4aredecreasedTheselectivity toCH4andC2-C4werehigher for theMEcatalystduringbothperiodsthismightbeattributedtotwofactslowCo0formationintheCoZr-Al2O3 (ME)catalystandthesmallpore sizeof thecarrier around4nm leading to internalmasstransferlimitationsfavoringthefasterH2 diffusionduetoitssmallersizecomparedtotheCOmoleculewhichdiffusesmoreslowlyThisledtohigherH2COratioswithinthecatalystparticlesthanatthepelletsurface

ConclusionForthefirsttimeZr-Aloxidesnanoparticlesweresynthesizedbythewater-in-oilmicroemulsionmethodThematerialpresentedahighZrdispersioninaluminaanditwashighlyhomogeneouswith uniform particle size narrow pore size distribution andhighsurfaceareaThismaterialwasusedascobaltsupportandcomparedwithsimilarmaterialpreparedbyZr impregnatedoncommercial alumina The presence of ZrO2-islands on aluminafavoredthedispersionanddegreeofreductionofcobaltwhile

the high Zr dispersion in the Zr-Al2O3 (ME) material hinderedZrO2crystallizationThisproducedamoreamorphousmaterialleading to ahigherdegreeof CoAl2O4 formationand thereforeincreased selectivity tomethaneand short-chainhydrocarbonsC2-C4ThecatalyticactivityandSC5+isfavouredbytheCoZr-Al2O3

(IM)catalystTheseresultsareattributedtothecatalystporosityandhigherCo0availabilityonthesurfaceHowevereven if thecobaltonZr-Al2O3nanoparticles(preparedbywater-in-oilmicroemulsion)isnotthebestcatalystforCOhydrogenationreactionwhen a high C5+ selectivity is desired the material has verygoodpropertiestobeconsideredforotherapplicationssuchasbasedmaterial in three-way-catalyst or as catalyst support forothercatalyticreactionlikehydrodesulphurizationortostabilizealuminaphaseswhenitisusedathightemperatures

Acknowledgments SwedishInternationalDevelopmentCooperationAgency(SIDA)NanoandesnetworkandEuropeanprojectCOSTActionCM1101forfinancialsupportSpecialthankstoDrEmanuelaNegro(DeftUniversityofTechnology)EdgarCardenas(LulearingUniversity)andCesarLeyvaPorras(CIMAVSC)formeasurementsofTEMSEMandHRTEMSTEM

0 200 400 600 800 1000 1200

804CoZr-Al2O3(ME)

CoZr-Al2O3(IM)

722

466

918

742608

350

252

925734

383

318CoAl2O3

Inte

nsity

(au

)

Temperature [degC]400 600 800 1000 1200

968754

428

989749

625

838744

606

CoAl2O3

CoZr-Al2O3 (IM)

CoZr-Al2O3 (ME)

Inte

nsity

(au

)

Temperature [degC]

Figure 5 TPRprofileforthefreshcatalyst(left)andafteractivationat350degCfor16h(right)

GHSV (Ncm3(gh-1) Catalysts XCO () SCH4a

() SC2-C4a () SC5+

a () SCO2 ()

6000 CoAl2O3 65 120 120 750 101500 CoAl2O3 280 85 110 800 056000 CoZr-Al2O3(IM) 120 100 78 810 122350 CoZr-Al2O3(IM) 310 76 60 860 046000 CoZr-Al2O3(ME) 40 200 160 610 301000 CoZr-Al2O3(ME) 270 170 150 670 10

Table 4COconversionlevelsandselectivitydataforthedifferentcatalystsa SelectivitiesareCO2-free

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4 VandeLoosdrechtJBotesFGCiobicaIMFerreiraACGibsonPetal(2013)FischerndashTropschSynthesisCatalystsandChemistryElsevierAmsterdampp525-557

5 GrenobleDCEstadtMMOllisDF(1981)Thechemistryandcatalysisofthewatergasshiftreaction1ThekineticsoversupportedmetalcatalystsJCatal6790-102

6 Tsakoumis NE Roslashnning M Borg Oslash Rytter E Holmen A (2010)Deactivation of cobalt based FischerndashTropsch catalysts A reviewCatalToday154162-182

7 BorgOslashEriSBlekkanEAStorsaeligterSWigumHetal(2007)FischerndashTropschsynthesisoverγ-alumina-supportedcobaltcatalystsEffectofsupportvariablesJCatal24889-100

8 MoradiGRBasirMMTaebAKiennemannA(2003)PromotionofCoSiO2FischerndashTropschcatalystswithzirconiumCatalCommun427-32

9 MiyazawaTHanaokaTShimuraKHirataS(2014)FischerndashTropschsynthesis over aCoSiO2 catalystmodifiedwithMn- andZrunderpracticalconditionsCatalCommun5736-39

10 Miyazawa T Hanaoka T Shimura K Hirata S (2013) Mn and Zrmodified CoSiO2 catalysts development in slurry-phase FischerndashTropschsynthesisAppliedCatalysisAGeneral46747-54

11 LiuYChenJFangKWangYSunY(2007)Alargepore-sizemesoporouszirconiasupportedcobaltcatalystwithgoodperformanceinFischerndashTropschsynthesisCatalCommun8945-949

12 Li ZWu J Yu JHanDWuL et al (2016)Effectof incorporationmanner of Zr on the CoSBA-15 catalyst for the FischerndashTropschsynthesisJMolCatalAChem424384-392

13 ShimuraKMiyazawaTHanaokaTHirataS(2015)FischerndashTropschsynthesisoveraluminasupportedcobaltcatalystEffectofpromoteradditionAppliedCatalysisAGeneral4941-11

14 Enache DI Roy-Auberger M Revel R (2014) Differences in thecharacteristics and catalytic properties of cobalt-based FischerndashTropsch catalysts supported on zirconia and alumina AppliedCatalysisAGeneral26851-60

15 RohrF LindvaringgOAHolmenABlekkanEA (2000)FischerndashTropschsynthesis over cobalt catalysts supported on zirconia-modifiedaluminaCatalToday58247-254

16 Jongsomjit B Panpranot J Goodwin JG (2003) Effect of zirconia-modifiedaluminaonthepropertiesofCoγ-Al2O3catalysts JCatal21566-77

17 Jacobs G Das TK Zhang Y Li J Racoillet G et al (2002) FischerndashTropsch synthesis support loading and promoter effects on thereducibility of cobalt catalysts Applied Catalysis A General 233263-281

18 Boutonnet M Marinas A Montes V Suaacuterez-Paris R Saacutenchez-Domınguez M (2016) Nanocatalysts Synthesis in Nanostructured

Liquid Media and Their Application in Energy and Production ofChemicalsinNanocolloidsElsevierAmsterdampp211-246

19 KombaiahKVijayaJJKennedyLJBououdinaMAl-LohedanHAetal(2017)StudiesonOpuntiadileniihawmediatedmultifunctionalZnFe2O4nanoparticlesOpticalmagneticandcatalyticapplicationsMaterChemPhys194153-164

20 Singh AK (2016) Structure Synthesis and Application ofNanoparticlesinEngineeredNanoparticlesAcademicPressBostonpp19-76

21 Eriksson S Nyleacuten U Rojas S Boutonnet M (2004) Preparationof catalysts from microemulsions and their applications inheterogeneouscatalysisApplCatalA265207-219

22 Pardo-Tarifa F Cabrera S Sanchez-Dominguez M Boutonnet M(2017) Ce-promoted CoAl 2 O 3 catalysts for Fischer-TropschsynthesisIntJHydrogenEnergy429754-9765

23 BoutonnetMSanchez-DominguezM(2017)MicroemulsiondropletstocatalyticallyactivenanoparticlesHowtheapplicationofcolloidaltools in catalysis aims towell design and efficient catalysts CatalToday28589-103

24 MisonoM(2013)ChemistryandCatalysisofMixedOxidesStudSurfSciCatal25-65

25 Sprague MJ (1985) Characterization of heterogeneous catalystsChemieIngenieurTechnik57430-430

26 LemaitreJLDelannayPGF(1984)CharacterizationofHeterogeneousCatalystsDenkerNewYork299-365

27 Schanke D Vada S Blekkan EA Hilmen AM Hoff A et al (1995)StudyofPt-promotedcobaltCOhydrogenationcatalystsJCatal15685-95

28 LoumlgdbergSLualdiMJaumlraringsSWalmsleyJCBlekkanEAetal(2010)Ontheselectivityofcobalt-basedFischerndashTropschcatalystsevidenceforacommonprecursorformethaneandlong-chainhydrocarbonsJCatal27484-98

29 ReuelRCBartholomewCH(1984)ThestoichiometriesofH2andCOadsorptionsoncobaltEffectsofsupportandpreparationJCatal8563-77

30 Jones RD Bartholomew CH (1988) Improved flow technique formeasurementofhydrogen chemisorptiononmetal catalystsApplCatal3977-88

31 Bhatia S Beltramini J Do DD (1990) Temperature programmedanalysisanditsapplicationsincatalyticsystemsCatalToday7309-438

32 Lualdi M Loumlgdberg S Regali F Boutonnet M Jaumlrarings S (2011)Investigation of mixtures of a Co-based catalyst and a Cu-basedcatalyst for the FischerndashTropsch synthesis with bio-syngas theimportanceofindigenouswaterTopCatal54977-985

33 Storsaeligter S Borg Oslash Blekkan EA Holmen A (2005) Study of theeffectofwateronFischerndashTropschsynthesisoversupportedcobaltcatalystsJCatal231405-419

34 Lualdi M (2012) Fischer-Tropsch Synthesis over Cobalt-basedCatalystsforBTLApplications

35 BoutonnetMLoumlgdbergSSvenssonEE(2008)RecentdevelopmentsintheapplicationofnanoparticlespreparedfromwomicroemulsionsinheterogeneouscatalysisCurrOpinColloidInterfaceSci13270-286

36 ChandradassJKimKH(2009)Effectofacidityonthecitrate-nitrate

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combustion synthesis of alumina-zirconia composite powderMetMaterInt151039-1043

37 Baudiacuten C (2014) Processing of Alumina and CorrespondingCompositesComprehensiveHardMaterials3172

38 ThommesMKanekoKNeimarkAVOlivier JP Rodriguez-ReinosoFetal(2015)Physisorptionofgaseswithspecialreferencetotheevaluation of surface area and pore size distribution Pure ApplChem871051-1069

39 MartiacutenezAPrietoGRollaacutenJ(2009)Nanofibrousγ-Al2O3assupportforCo-basedFischerndashTropschcatalystsponderingtherelevanceofdiffusionalanddispersioneffectsoncatalyticperformance JCatal263292-305

40 Liu C Li J Zhang Y Chen S Zhu J et al (2012) FischerndashTropschsynthesisovercobaltcatalystssupportedonnanostructuredaluminawithvariousmorphologiesJMolCatalAChem363335-342

41 CastnerDGWatsonPRChanIY(1990)X-rayabsorptionspectroscopy

X-rayphotoelectronspectroscopyandanalyticalelectronmicroscopystudiesofcobaltcatalysts2HydrogenreductionpropertiesJPhysChem94819-828

42 OslashyvindBMagnusRSOslashlviSAndersH(2007)Identificationofcobaltspecies during temperature programmed reduction of Fischer-TropschcatalystsStudiesinSurfaceScienceandCatalysis163255-272

43 Topsoslashe NY Topsoslashe H (1982) Adsorption studies onhydrodesulfurization catalysts I Infrared and volumetric study ofNOadsorptiononalumina-supportedCoMoandCo-MocatalystsintheircalcinedstateJCatal75354-374

44 SimionatoMAssafEM(2003)Preparationandcharacterizationofalumina-supportedCoandAgCocatalystsMaterRes6535-539

45 VandeLoosdrechtJVanderHaarMVanderKraanAMVanDillenAJGeusJW(1997)PreparationandpropertiesofsupportedcobaltcatalystsforFischer-TropschsynthesisApplCatalA150365-376

Page 3: Synthesis and Characterization of Novel Zr-Al2O3 ... Prepared2 by Microemulsion Method and Its Use as Cobalt Catalyst Support for the CO Hydrogenation Reaction. Synth Catal. 2017,

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2910ataflowof5volH2inArinarangeoftemperaturesfrom30degC to 930degC (heating rate 10degCmin) The H2 consumptionwas monitored during the study by the difference in thermalconductivity between the inlet and outlet gases The degreeof reduction (DOR ) was calculated using H2-TPR of the in-situ reducedcatalysts015gof the freshcatalystwasreducedat 350degC (1degCmin) for 16 h in flowing H2 then flushed withheliumgas for30minAfterwards theheliumwaschanged to5 volH2 inAr and the temperaturewas increased from350to 930degC (10degCmin) and the H2 consumption was monitoredThe TCD was calibrated with Ag2O as standard The DOR wascalculated assuming that unreduced cobalt after the reductionpre-treatmentwasintheformofCo2+accordingto

1 ATCD fDORXCo AWCo

times= minus

divide

whereATCD is the integrationof theTCDsignalnormalizedpermasscatalystAWCoistheatomicweightofCo(589gmol)fisacalibrationfactorcorrelatingtheareaoftheTCDsignalandtheH2 consumedXCoisthecobaltloading(12Co)

Thecobaltdispersion(D)andthecobaltcrystallitesize(d(Codeg)nm) was calculated by hydrogen static chemisorption on thereduced catalysts The measurements were performed on aMicromeritics ASAP 202degC unit at 35degC after reducing about015gofthefreshcatalystsunderthesameconditionsasinTPRanalysis(H2flowat350degCfor16h(heatingrate1degCmin))

Themorphologyofthesupportsandfinalcatalystswasstudiedbyhighresolution-scanningelectronmicroscopy(HR-SEM)usinganXHR-SEMMagellan400instrumentsuppliedbytheFEICompanyThesampleswere investigatedusinga lowacceleratingvoltageandnoconductivecoating

Transmissionelectronmicroscopy(TEM)analysiswasperformedusingaPhilipsCM300UT-FEGelectronmicroscopewithapointresolution of 017 nm information limit of 01 nmwhichwasoperated at 200 kV in which images were acquired with aTVIPS CCD camera The samples were prepared by immersingaQuantifoilRcoppermicrogrid inafreshcatalystdispersedinethanol

Catalytic testingCO hydrogenation was tested at operating conditions similarto Fischer-Tropsch synthesis Experimentswereperformed in astainless-steelfixed-bedreactor(id9mm)atprocessconditions210degC20barmolarH2COratio=21Amixtureof1gofcatalystwith a pellet size between 53ndash90 μm was diluted and mixedwith5gofSiC(foraneventemperatureprofile)andthereafterplaced in the reactor [2832]Prior to the reaction thecatalystwasactivatedby reducing it in situwithhydrogenat350degC for16hatatmosphericpressureAfteractivation thereactorwascooleddownto180degCandthenflushedwithHebeforeincreasingthe pressure to 20 bar The catalysts were tested during twoperiodsfirstatasyngasflowof100cm3min (NTP)and in thesecond period the gas flowwas adjusted in order to obtain aCO conversion of 30 [732-34] The heavy hydrocarbons andmostof thewaterwere condensed in two traps kept at 120degCand room-temperature respectivelyTheproductgases leaving

the traps were depressurized and analyzed on-line with a gaschromatograph (GC) Agilent 6890 equipped with a thermalconductivity detector (TCD) and a flame ionization detector(FID)H2N2COCH4andCO2wereseparatedbyaCarbosieveIIpackedcolumnandanalyzedontheTCDThepercentageofCOconversionwascalculatedby

( ) 100in out

in

CO COCOconv molCOminus

= times

C1ndashC6 products were separated by an alumina-plot column andquantifiedon theFIDdetector fromwhich itwaspossibletodeterminetheC5+selectivity(SC5+)TheCO2-freeSC5+(ieSC5+ ifexcludingCO2 fromtheC-atombalance) isdefinedasfollows[2832]

SC5+=100minus(SC1+SC2+SC3+SC4)CO2free

Results and DiscussionSynthesis approachZr-Al co-precipitated in water-in-oil microemulsion Severalmicroemulsionswerepreparedinordertodefinethecompositionandtemperatureofthewatersurfactantoil (WSO)systematwhich themicroemulsionwas formedand stable The selectedweightratioinpercentageswas79264657(Table 1)TheZr-Al2O3precursorwasformedbycollisionandcoalescenceofwaterdropletsbetweenmicroemulsions1and2(ME1andME2)Oxo-hydroxocomplexesof zirconiumandaluminumwereproducedwhen the base came in contact with the metal initiating thenucleationand formationof thefirstparticles inside thewaterdroplets [1835] The simultaneous co-precipitation of theprecursors inside thewater droplets favors in thisway a gooddispersionofZrinaluminaanduniformgrowthoftheparticlesIn addition the EDX spectra of the material showed AlZrCoatomicratios(Table 2)similartotheaddedmetalsTheseresultsshowthatbothZrandAlprecipitatedduringthesynthesisandnolossofmetalwasdetected

Wetness impregnation Thecommercialaluminausedassupporthasapseudoϒ-Al2O3porousstructureThisframeworkallowsthedeposition of zirconiumfirst and after cobalt oxides inside theporesandonthesurfaceofthealuminaDuringthecalcinationstepdecompositionoftheprecursorsandreactionsbetweentheZrCoandϒ-Al2O3mightoccur

Characterization of the materialsX-Ray diffractograms The X-ray diffractograms of the carriersand Co-catalysts are illustrated in Figure 1 The Zr-Al2O3(ME)support presents a low crystalline ϒ-Al2O3 phase In addition

Material AlZr Atomic ratio AlCo Atomic ratio

Zr-Al2O3(IM) 79 -Z-Al2O3(ME) 79 -

CoZr-Al2O3(IM) 81 68CoZr-Al2O3(ME) 79 71

Table 2 RepresentativeEDXelementalanalysisofthesupportsandthecatalysts

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no Zr specieswere detectedwhichmight be attributed to theapplied synthesismethodOne explanation could be that Zr isencapsulated in the aluminamatrix and consequently Zr oxidespeciescrystalformationwasinhibited[3637]IncontrasttheZr-Al2O3(IM)materialpresentscharacteristicpeaksforϒ-Al2O3andabandat2θ=32degassignedtoametastableZrO2withorthorhombicstructure(Figure 1)

AfterCodepositiontheXRDpatterns(Figure 1 right)showedahighlycrystallineCo3O4specieswereformed inall thecatalystswithsimilarcrystallitesizesofapproximately11nm(Figure 1 and Table 3)ThusitcanbeconcludedthatthepresenceofZrdoesnotaffecttheCo3O4particlesize

N2 physisorption ThecatalystporosityispresentedinFigure 2TheisothermscorrespondtotypeIV[38]ThehysteresisloopforCoZr-Al2O3(ME)correspondstotypeH2(b)[38]associatedwithcomplexporenetworksconsistingofporeswithill-definedshapesinthemesoporerangeMaterialswithtexturalporosityformedbyvoidsbetweenparticlescanbeassociatewithtypeH2(b)Inadditionthismaterialshowednarrowporesizedistribution CoZr-Al2O3(IM)andAl2O3supportsshowedtypeH3hysteresisloop[38] correspondent tomaterialswithnon-rigidaggregatesandwideporesizedistributionlikeamorphousaluminaThecarrierisothermsweresimilar andthereforenotincludedin Figure 2

Thesurfaceareaforallmaterialswasbetween190and248m2g(Table 3) IncorporationofCoandorZrphasesonaluminaleadstoadecreaseinBETsurfaceareaandporevolume(Table 3)duetopartialporeblockageofthedepositedoxidesinsidethepores[3940]TheCo3O4particlesizewassmallerthantheAl2O3 andZr-Al2O3(IM)poresizethereforeCo3O4depositionisfavoredinsidethe pores On the other hand Zr-Al2O3(ME) had smaller porediameter sizes than the Co3O4 particles (Table 3) which leadstotheconclusionthatsomeoftheCo3O4wasdepositedonthecarriersurface

Scanning and transmission electron microscopy The Zr-Al2O3(ME) and CoZr-Al2O3(ME)morphology (Figure 3) showednon-agglomerateduniformparticlesizedistributionHoweverCoAl2O3 Zr-Al2O3(IM) and CoZr-Al2O3(IM) showed heterogeneoussphericalagglomerationsofsmallerparticlesof12080and80μmrespectivelyTheseagglomerationsareattributedtoZrandorCodepositionZr-Al2O3(ME)doesnotagglomerateaftercobaltdeposition (Figure 3) Basedon thesefindings it is consideredthat Zr prevents particle agglomeration especially when Zr ishighlydispersed

For a better understanding of the species and morphology inthe promoted-catalysts TEM pictures were taken (Figure 4)

2θ (deg)

Figure 1 X-raydiffractogramsofthecarriers(left)calcinedat500degCfor6handcobalt-catalysts(right)calcinedat350degCfor10h

Sample

N2 Physisorption XRD Chemisorption TPRBET

Surface area (m2g)

Total Pore volumea

(cm3g)

Average Pore diameter

(nm) b

Particle size Co3O4 (nm) c

Particle size

Co0 (nm) dParticle size Co0 (nm) e

Metal Dispersion D f DOR i

Al2O3 283 11 147 - - - - -Zr-Al2O3 (IM) 239 08 140 - - - - -Zr-Al2O3(ME) 211 03 65 - - - - -CoAl2O3 248 09 140 105 79 26 45 30

CoZr-Al2O3(IM) 227 07 127 113 85 27 80 47CoZrAl2O3(ME) 191 03 58 113 85 41 70 11

Table 3Physicochemicalcharacterizationofthesupportsandcatalysts aDeterminedfromasinglepointofadsorptionatPP0=0998bEstimated

byBJHformalism(adsorptionbranch)cAveragecrystallitesizeofCo3O4estimatedfromScherrerequationdAccordingwithd(Co0)=075d(Co3O4)

eAccordingtod(Co0)H fMetaldispersionafterreductionat350degCfor16hinH2iDegreofreduction(DOR)fromTPRofreducedcatalysts

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H2-Temperature programmed reduction A typical TPR profileforallthecatalystsisshowninFigure 5IngeneralthefirsttwopeakscorrespondtothereductionofCo3O4+H2rarr3CoO+H2O [41]and3CoO+3H2rarr3Co0+3H2O[42]Thepeakaround700degCis attributed toCo3AlO6 (Co3O4-AlO2) andorCoO-Al2O3and thepeakat900degCcorrespondstoCoAl2O4[43-45]

Co3O4 in CoZr-Al2O3(ME) was harder to reduce as aconsequence the reduction temperature was shifted towardshigher temperature compared to the other catalysts The lackof crystallinity in the ME carrier favored the cobalt-aluminateformationandalsoitsreductiontemperature

TheTPRforCoZr-Al2O3(IM)presentssimilarpeaksasforCoAl2O3 withthedifferencethatthereductiontemperaturewaslowerbyabout 50degC In addition an extra H2 uptakewas seen at 608degCwhichcancorrespondtothepartialreductionofZrTheamountof cobalt aluminate specieswasdecreasedcomparedwithCoAl2O3attributedtothepresenceofZrCoAl2O4(spinel)wasnotdetected by the XRD technique since its diffractogram peaksoverlapstheCo3O4peaks

Additionally TPR experiments (Figure 5 right)were performedafter the catalyst activation in order to identify the unreducedcobalt amount and consequently the degree of reduction(DOR) (ie from 350 to 930degC in H2) Co3O4 in CoZr-Al2O3(IM)iscompletelyreducedaftercatalystactivationwithaDORof47whiletheDORforCoAl2O3andforZr-Al2O3(ME)is30and11 respectively (Table 3 and Figure 5) Thereafter it can beconcludedthatthepresenceofZrinislandsasisthecaseofCoZr-Al2O3(IM)decreasethecobalt-aluminainteractionsfavoringinthisway amoremetallic formationwhich is required for a COhydrogenationreaction

Interestingtonoteinallthecatalysts(Figure 5 right)isthattheunreducedcobaltspecies(peaksaround700and900degC)shiftedthe reduction temperature to higher temperatures comparedwiththefirstTPRanalysis(Figure 5 left)Theexplanationgivenisthatduringcatalystsactivationtheremainingunreduced-cobaltintheformofCodeg interactswithwater(producedbythemetalreduction) to form Co-aluminate which is reduced at a highertemperature[15]

Table 3 presentsthedispersionofmetalliccobaltCodegcalculatedbyH2chemisorption(illustratedinexperimentalpart)TheresultsshowthatCodegdispersionisquitesimilar inCoZr-Al2O3(IM) andCoZr-Al2O3(ME) These results compared with CoAl2O3 arehighersoit isconcludedthatZrfavorsthedispersionofcobaltinaluminasupportInadditionthemeasuredCodegparticlesizebythistechniqueandbyTEMishigherthanthecalculatedfromtheScherrerequation fromwhich it canbeconcluded thatduringcatalystactivationthemetallicparticlesaresinteredThiseffectishigher inCoZr-Al2O3(ME)andoneof theexplanationsmightbeduetothetexturalporosityandthelackofstructuralporositywhichmakesthecobalt-sinteringeasier

Catalytic testComparingCOconversionsforallthecatalystsafter25hofsyngasstream(H2 CO=21)(Table 4)thecatalystactivitydecreasesinthefollowingorderCoZr-Al2O3(IM)gtCoAl2O3gtCoZr-Al2O3(ME)The

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Figure 2 TheN2 adsorption-desorption isotherms and pore sizedistributioncurvesforthecobaltcatalysts

CoZr-Al2O3(ME) shows a homogeneous material formed byagglomerated nanoparticles CoZr-Al2O3(ME) shows carrierparticlesizesbetween4-7nmandCo3O4cubiccrystals(Figure 4a)STEM-EDXmappingresultsshowahomogeneousdistributionofZronCoZr-Al2O3(ME) (Figure 4a)ThispicturedemonstrateshowtheMEtechniquecanbeappliedforthesynthesisofhighlydisperseoxidepromoteronacarrierTheZrdispersiononaluminainCoZr-Al2O3(IM)(Figure 4b)waslowerformingZr-richislandsontheAl2O3 surfaceFurthermorethecobaltdepositionseemstobebetterintheMEmaterialthanintheZr-impregnatedmaterial

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Figure 3 SEMpicturesforthecarrierandthecobaltcatalysts

a)CoZr-Al2O3(ME) b) CoZr-Al2O3(IM )

20 nm 300 nm

600 nm

Zr Zr

Al Co Co Al

300 nm

4 nm

Figure 4 RepresentativeSTEM-EDXelementalmappingfora)CoZr-Al2O3(ME)andb)CoZr-Al2O3(IM)

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resultsarerelatedtothehighertheDOR(degreeofreductionofCo)thehighertheCOconversioninperiodone(Table 3)

InallthecasestheselectivityisaffectedbytheCOconversionthe higher the CO conversion the higher the C5+ selectivity(SC5+)andasaconsequencetheselectivitytoCH4andC2-C4aredecreasedTheselectivity toCH4andC2-C4werehigher for theMEcatalystduringbothperiodsthismightbeattributedtotwofactslowCo0formationintheCoZr-Al2O3 (ME)catalystandthesmallpore sizeof thecarrier around4nm leading to internalmasstransferlimitationsfavoringthefasterH2 diffusionduetoitssmallersizecomparedtotheCOmoleculewhichdiffusesmoreslowlyThisledtohigherH2COratioswithinthecatalystparticlesthanatthepelletsurface

ConclusionForthefirsttimeZr-Aloxidesnanoparticlesweresynthesizedbythewater-in-oilmicroemulsionmethodThematerialpresentedahighZrdispersioninaluminaanditwashighlyhomogeneouswith uniform particle size narrow pore size distribution andhighsurfaceareaThismaterialwasusedascobaltsupportandcomparedwithsimilarmaterialpreparedbyZr impregnatedoncommercial alumina The presence of ZrO2-islands on aluminafavoredthedispersionanddegreeofreductionofcobaltwhile

the high Zr dispersion in the Zr-Al2O3 (ME) material hinderedZrO2crystallizationThisproducedamoreamorphousmaterialleading to ahigherdegreeof CoAl2O4 formationand thereforeincreased selectivity tomethaneand short-chainhydrocarbonsC2-C4ThecatalyticactivityandSC5+isfavouredbytheCoZr-Al2O3

(IM)catalystTheseresultsareattributedtothecatalystporosityandhigherCo0availabilityonthesurfaceHowevereven if thecobaltonZr-Al2O3nanoparticles(preparedbywater-in-oilmicroemulsion)isnotthebestcatalystforCOhydrogenationreactionwhen a high C5+ selectivity is desired the material has verygoodpropertiestobeconsideredforotherapplicationssuchasbasedmaterial in three-way-catalyst or as catalyst support forothercatalyticreactionlikehydrodesulphurizationortostabilizealuminaphaseswhenitisusedathightemperatures

Acknowledgments SwedishInternationalDevelopmentCooperationAgency(SIDA)NanoandesnetworkandEuropeanprojectCOSTActionCM1101forfinancialsupportSpecialthankstoDrEmanuelaNegro(DeftUniversityofTechnology)EdgarCardenas(LulearingUniversity)andCesarLeyvaPorras(CIMAVSC)formeasurementsofTEMSEMandHRTEMSTEM

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)

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Figure 5 TPRprofileforthefreshcatalyst(left)andafteractivationat350degCfor16h(right)

GHSV (Ncm3(gh-1) Catalysts XCO () SCH4a

() SC2-C4a () SC5+

a () SCO2 ()

6000 CoAl2O3 65 120 120 750 101500 CoAl2O3 280 85 110 800 056000 CoZr-Al2O3(IM) 120 100 78 810 122350 CoZr-Al2O3(IM) 310 76 60 860 046000 CoZr-Al2O3(ME) 40 200 160 610 301000 CoZr-Al2O3(ME) 270 170 150 670 10

Table 4COconversionlevelsandselectivitydataforthedifferentcatalystsa SelectivitiesareCO2-free

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2 DryME(2002)Thefischerndashtropschprocess1950ndash2000CatalToday71227-241

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4 VandeLoosdrechtJBotesFGCiobicaIMFerreiraACGibsonPetal(2013)FischerndashTropschSynthesisCatalystsandChemistryElsevierAmsterdampp525-557

5 GrenobleDCEstadtMMOllisDF(1981)Thechemistryandcatalysisofthewatergasshiftreaction1ThekineticsoversupportedmetalcatalystsJCatal6790-102

6 Tsakoumis NE Roslashnning M Borg Oslash Rytter E Holmen A (2010)Deactivation of cobalt based FischerndashTropsch catalysts A reviewCatalToday154162-182

7 BorgOslashEriSBlekkanEAStorsaeligterSWigumHetal(2007)FischerndashTropschsynthesisoverγ-alumina-supportedcobaltcatalystsEffectofsupportvariablesJCatal24889-100

8 MoradiGRBasirMMTaebAKiennemannA(2003)PromotionofCoSiO2FischerndashTropschcatalystswithzirconiumCatalCommun427-32

9 MiyazawaTHanaokaTShimuraKHirataS(2014)FischerndashTropschsynthesis over aCoSiO2 catalystmodifiedwithMn- andZrunderpracticalconditionsCatalCommun5736-39

10 Miyazawa T Hanaoka T Shimura K Hirata S (2013) Mn and Zrmodified CoSiO2 catalysts development in slurry-phase FischerndashTropschsynthesisAppliedCatalysisAGeneral46747-54

11 LiuYChenJFangKWangYSunY(2007)Alargepore-sizemesoporouszirconiasupportedcobaltcatalystwithgoodperformanceinFischerndashTropschsynthesisCatalCommun8945-949

12 Li ZWu J Yu JHanDWuL et al (2016)Effectof incorporationmanner of Zr on the CoSBA-15 catalyst for the FischerndashTropschsynthesisJMolCatalAChem424384-392

13 ShimuraKMiyazawaTHanaokaTHirataS(2015)FischerndashTropschsynthesisoveraluminasupportedcobaltcatalystEffectofpromoteradditionAppliedCatalysisAGeneral4941-11

14 Enache DI Roy-Auberger M Revel R (2014) Differences in thecharacteristics and catalytic properties of cobalt-based FischerndashTropsch catalysts supported on zirconia and alumina AppliedCatalysisAGeneral26851-60

15 RohrF LindvaringgOAHolmenABlekkanEA (2000)FischerndashTropschsynthesis over cobalt catalysts supported on zirconia-modifiedaluminaCatalToday58247-254

16 Jongsomjit B Panpranot J Goodwin JG (2003) Effect of zirconia-modifiedaluminaonthepropertiesofCoγ-Al2O3catalysts JCatal21566-77

17 Jacobs G Das TK Zhang Y Li J Racoillet G et al (2002) FischerndashTropsch synthesis support loading and promoter effects on thereducibility of cobalt catalysts Applied Catalysis A General 233263-281

18 Boutonnet M Marinas A Montes V Suaacuterez-Paris R Saacutenchez-Domınguez M (2016) Nanocatalysts Synthesis in Nanostructured

Liquid Media and Their Application in Energy and Production ofChemicalsinNanocolloidsElsevierAmsterdampp211-246

19 KombaiahKVijayaJJKennedyLJBououdinaMAl-LohedanHAetal(2017)StudiesonOpuntiadileniihawmediatedmultifunctionalZnFe2O4nanoparticlesOpticalmagneticandcatalyticapplicationsMaterChemPhys194153-164

20 Singh AK (2016) Structure Synthesis and Application ofNanoparticlesinEngineeredNanoparticlesAcademicPressBostonpp19-76

21 Eriksson S Nyleacuten U Rojas S Boutonnet M (2004) Preparationof catalysts from microemulsions and their applications inheterogeneouscatalysisApplCatalA265207-219

22 Pardo-Tarifa F Cabrera S Sanchez-Dominguez M Boutonnet M(2017) Ce-promoted CoAl 2 O 3 catalysts for Fischer-TropschsynthesisIntJHydrogenEnergy429754-9765

23 BoutonnetMSanchez-DominguezM(2017)MicroemulsiondropletstocatalyticallyactivenanoparticlesHowtheapplicationofcolloidaltools in catalysis aims towell design and efficient catalysts CatalToday28589-103

24 MisonoM(2013)ChemistryandCatalysisofMixedOxidesStudSurfSciCatal25-65

25 Sprague MJ (1985) Characterization of heterogeneous catalystsChemieIngenieurTechnik57430-430

26 LemaitreJLDelannayPGF(1984)CharacterizationofHeterogeneousCatalystsDenkerNewYork299-365

27 Schanke D Vada S Blekkan EA Hilmen AM Hoff A et al (1995)StudyofPt-promotedcobaltCOhydrogenationcatalystsJCatal15685-95

28 LoumlgdbergSLualdiMJaumlraringsSWalmsleyJCBlekkanEAetal(2010)Ontheselectivityofcobalt-basedFischerndashTropschcatalystsevidenceforacommonprecursorformethaneandlong-chainhydrocarbonsJCatal27484-98

29 ReuelRCBartholomewCH(1984)ThestoichiometriesofH2andCOadsorptionsoncobaltEffectsofsupportandpreparationJCatal8563-77

30 Jones RD Bartholomew CH (1988) Improved flow technique formeasurementofhydrogen chemisorptiononmetal catalystsApplCatal3977-88

31 Bhatia S Beltramini J Do DD (1990) Temperature programmedanalysisanditsapplicationsincatalyticsystemsCatalToday7309-438

32 Lualdi M Loumlgdberg S Regali F Boutonnet M Jaumlrarings S (2011)Investigation of mixtures of a Co-based catalyst and a Cu-basedcatalyst for the FischerndashTropsch synthesis with bio-syngas theimportanceofindigenouswaterTopCatal54977-985

33 Storsaeligter S Borg Oslash Blekkan EA Holmen A (2005) Study of theeffectofwateronFischerndashTropschsynthesisoversupportedcobaltcatalystsJCatal231405-419

34 Lualdi M (2012) Fischer-Tropsch Synthesis over Cobalt-basedCatalystsforBTLApplications

35 BoutonnetMLoumlgdbergSSvenssonEE(2008)RecentdevelopmentsintheapplicationofnanoparticlespreparedfromwomicroemulsionsinheterogeneouscatalysisCurrOpinColloidInterfaceSci13270-286

36 ChandradassJKimKH(2009)Effectofacidityonthecitrate-nitrate

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combustion synthesis of alumina-zirconia composite powderMetMaterInt151039-1043

37 Baudiacuten C (2014) Processing of Alumina and CorrespondingCompositesComprehensiveHardMaterials3172

38 ThommesMKanekoKNeimarkAVOlivier JP Rodriguez-ReinosoFetal(2015)Physisorptionofgaseswithspecialreferencetotheevaluation of surface area and pore size distribution Pure ApplChem871051-1069

39 MartiacutenezAPrietoGRollaacutenJ(2009)Nanofibrousγ-Al2O3assupportforCo-basedFischerndashTropschcatalystsponderingtherelevanceofdiffusionalanddispersioneffectsoncatalyticperformance JCatal263292-305

40 Liu C Li J Zhang Y Chen S Zhu J et al (2012) FischerndashTropschsynthesisovercobaltcatalystssupportedonnanostructuredaluminawithvariousmorphologiesJMolCatalAChem363335-342

41 CastnerDGWatsonPRChanIY(1990)X-rayabsorptionspectroscopy

X-rayphotoelectronspectroscopyandanalyticalelectronmicroscopystudiesofcobaltcatalysts2HydrogenreductionpropertiesJPhysChem94819-828

42 OslashyvindBMagnusRSOslashlviSAndersH(2007)Identificationofcobaltspecies during temperature programmed reduction of Fischer-TropschcatalystsStudiesinSurfaceScienceandCatalysis163255-272

43 Topsoslashe NY Topsoslashe H (1982) Adsorption studies onhydrodesulfurization catalysts I Infrared and volumetric study ofNOadsorptiononalumina-supportedCoMoandCo-MocatalystsintheircalcinedstateJCatal75354-374

44 SimionatoMAssafEM(2003)Preparationandcharacterizationofalumina-supportedCoandAgCocatalystsMaterRes6535-539

45 VandeLoosdrechtJVanderHaarMVanderKraanAMVanDillenAJGeusJW(1997)PreparationandpropertiesofsupportedcobaltcatalystsforFischer-TropschsynthesisApplCatalA150365-376

Page 4: Synthesis and Characterization of Novel Zr-Al2O3 ... Prepared2 by Microemulsion Method and Its Use as Cobalt Catalyst Support for the CO Hydrogenation Reaction. Synth Catal. 2017,

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no Zr specieswere detectedwhichmight be attributed to theapplied synthesismethodOne explanation could be that Zr isencapsulated in the aluminamatrix and consequently Zr oxidespeciescrystalformationwasinhibited[3637]IncontrasttheZr-Al2O3(IM)materialpresentscharacteristicpeaksforϒ-Al2O3andabandat2θ=32degassignedtoametastableZrO2withorthorhombicstructure(Figure 1)

AfterCodepositiontheXRDpatterns(Figure 1 right)showedahighlycrystallineCo3O4specieswereformed inall thecatalystswithsimilarcrystallitesizesofapproximately11nm(Figure 1 and Table 3)ThusitcanbeconcludedthatthepresenceofZrdoesnotaffecttheCo3O4particlesize

N2 physisorption ThecatalystporosityispresentedinFigure 2TheisothermscorrespondtotypeIV[38]ThehysteresisloopforCoZr-Al2O3(ME)correspondstotypeH2(b)[38]associatedwithcomplexporenetworksconsistingofporeswithill-definedshapesinthemesoporerangeMaterialswithtexturalporosityformedbyvoidsbetweenparticlescanbeassociatewithtypeH2(b)Inadditionthismaterialshowednarrowporesizedistribution CoZr-Al2O3(IM)andAl2O3supportsshowedtypeH3hysteresisloop[38] correspondent tomaterialswithnon-rigidaggregatesandwideporesizedistributionlikeamorphousaluminaThecarrierisothermsweresimilar andthereforenotincludedin Figure 2

Thesurfaceareaforallmaterialswasbetween190and248m2g(Table 3) IncorporationofCoandorZrphasesonaluminaleadstoadecreaseinBETsurfaceareaandporevolume(Table 3)duetopartialporeblockageofthedepositedoxidesinsidethepores[3940]TheCo3O4particlesizewassmallerthantheAl2O3 andZr-Al2O3(IM)poresizethereforeCo3O4depositionisfavoredinsidethe pores On the other hand Zr-Al2O3(ME) had smaller porediameter sizes than the Co3O4 particles (Table 3) which leadstotheconclusionthatsomeoftheCo3O4wasdepositedonthecarriersurface

Scanning and transmission electron microscopy The Zr-Al2O3(ME) and CoZr-Al2O3(ME)morphology (Figure 3) showednon-agglomerateduniformparticlesizedistributionHoweverCoAl2O3 Zr-Al2O3(IM) and CoZr-Al2O3(IM) showed heterogeneoussphericalagglomerationsofsmallerparticlesof12080and80μmrespectivelyTheseagglomerationsareattributedtoZrandorCodepositionZr-Al2O3(ME)doesnotagglomerateaftercobaltdeposition (Figure 3) Basedon thesefindings it is consideredthat Zr prevents particle agglomeration especially when Zr ishighlydispersed

For a better understanding of the species and morphology inthe promoted-catalysts TEM pictures were taken (Figure 4)

2θ (deg)

Figure 1 X-raydiffractogramsofthecarriers(left)calcinedat500degCfor6handcobalt-catalysts(right)calcinedat350degCfor10h

Sample

N2 Physisorption XRD Chemisorption TPRBET

Surface area (m2g)

Total Pore volumea

(cm3g)

Average Pore diameter

(nm) b

Particle size Co3O4 (nm) c

Particle size

Co0 (nm) dParticle size Co0 (nm) e

Metal Dispersion D f DOR i

Al2O3 283 11 147 - - - - -Zr-Al2O3 (IM) 239 08 140 - - - - -Zr-Al2O3(ME) 211 03 65 - - - - -CoAl2O3 248 09 140 105 79 26 45 30

CoZr-Al2O3(IM) 227 07 127 113 85 27 80 47CoZrAl2O3(ME) 191 03 58 113 85 41 70 11

Table 3Physicochemicalcharacterizationofthesupportsandcatalysts aDeterminedfromasinglepointofadsorptionatPP0=0998bEstimated

byBJHformalism(adsorptionbranch)cAveragecrystallitesizeofCo3O4estimatedfromScherrerequationdAccordingwithd(Co0)=075d(Co3O4)

eAccordingtod(Co0)H fMetaldispersionafterreductionat350degCfor16hinH2iDegreofreduction(DOR)fromTPRofreducedcatalysts

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H2-Temperature programmed reduction A typical TPR profileforallthecatalystsisshowninFigure 5IngeneralthefirsttwopeakscorrespondtothereductionofCo3O4+H2rarr3CoO+H2O [41]and3CoO+3H2rarr3Co0+3H2O[42]Thepeakaround700degCis attributed toCo3AlO6 (Co3O4-AlO2) andorCoO-Al2O3and thepeakat900degCcorrespondstoCoAl2O4[43-45]

Co3O4 in CoZr-Al2O3(ME) was harder to reduce as aconsequence the reduction temperature was shifted towardshigher temperature compared to the other catalysts The lackof crystallinity in the ME carrier favored the cobalt-aluminateformationandalsoitsreductiontemperature

TheTPRforCoZr-Al2O3(IM)presentssimilarpeaksasforCoAl2O3 withthedifferencethatthereductiontemperaturewaslowerbyabout 50degC In addition an extra H2 uptakewas seen at 608degCwhichcancorrespondtothepartialreductionofZrTheamountof cobalt aluminate specieswasdecreasedcomparedwithCoAl2O3attributedtothepresenceofZrCoAl2O4(spinel)wasnotdetected by the XRD technique since its diffractogram peaksoverlapstheCo3O4peaks

Additionally TPR experiments (Figure 5 right)were performedafter the catalyst activation in order to identify the unreducedcobalt amount and consequently the degree of reduction(DOR) (ie from 350 to 930degC in H2) Co3O4 in CoZr-Al2O3(IM)iscompletelyreducedaftercatalystactivationwithaDORof47whiletheDORforCoAl2O3andforZr-Al2O3(ME)is30and11 respectively (Table 3 and Figure 5) Thereafter it can beconcludedthatthepresenceofZrinislandsasisthecaseofCoZr-Al2O3(IM)decreasethecobalt-aluminainteractionsfavoringinthisway amoremetallic formationwhich is required for a COhydrogenationreaction

Interestingtonoteinallthecatalysts(Figure 5 right)isthattheunreducedcobaltspecies(peaksaround700and900degC)shiftedthe reduction temperature to higher temperatures comparedwiththefirstTPRanalysis(Figure 5 left)Theexplanationgivenisthatduringcatalystsactivationtheremainingunreduced-cobaltintheformofCodeg interactswithwater(producedbythemetalreduction) to form Co-aluminate which is reduced at a highertemperature[15]

Table 3 presentsthedispersionofmetalliccobaltCodegcalculatedbyH2chemisorption(illustratedinexperimentalpart)TheresultsshowthatCodegdispersionisquitesimilar inCoZr-Al2O3(IM) andCoZr-Al2O3(ME) These results compared with CoAl2O3 arehighersoit isconcludedthatZrfavorsthedispersionofcobaltinaluminasupportInadditionthemeasuredCodegparticlesizebythistechniqueandbyTEMishigherthanthecalculatedfromtheScherrerequation fromwhich it canbeconcluded thatduringcatalystactivationthemetallicparticlesaresinteredThiseffectishigher inCoZr-Al2O3(ME)andoneof theexplanationsmightbeduetothetexturalporosityandthelackofstructuralporositywhichmakesthecobalt-sinteringeasier

Catalytic testComparingCOconversionsforallthecatalystsafter25hofsyngasstream(H2 CO=21)(Table 4)thecatalystactivitydecreasesinthefollowingorderCoZr-Al2O3(IM)gtCoAl2O3gtCoZr-Al2O3(ME)The

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Figure 2 TheN2 adsorption-desorption isotherms and pore sizedistributioncurvesforthecobaltcatalysts

CoZr-Al2O3(ME) shows a homogeneous material formed byagglomerated nanoparticles CoZr-Al2O3(ME) shows carrierparticlesizesbetween4-7nmandCo3O4cubiccrystals(Figure 4a)STEM-EDXmappingresultsshowahomogeneousdistributionofZronCoZr-Al2O3(ME) (Figure 4a)ThispicturedemonstrateshowtheMEtechniquecanbeappliedforthesynthesisofhighlydisperseoxidepromoteronacarrierTheZrdispersiononaluminainCoZr-Al2O3(IM)(Figure 4b)waslowerformingZr-richislandsontheAl2O3 surfaceFurthermorethecobaltdepositionseemstobebetterintheMEmaterialthanintheZr-impregnatedmaterial

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Figure 3 SEMpicturesforthecarrierandthecobaltcatalysts

a)CoZr-Al2O3(ME) b) CoZr-Al2O3(IM )

20 nm 300 nm

600 nm

Zr Zr

Al Co Co Al

300 nm

4 nm

Figure 4 RepresentativeSTEM-EDXelementalmappingfora)CoZr-Al2O3(ME)andb)CoZr-Al2O3(IM)

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Synthesis and Catalysis Open AccessISSN 2574-0431

resultsarerelatedtothehighertheDOR(degreeofreductionofCo)thehighertheCOconversioninperiodone(Table 3)

InallthecasestheselectivityisaffectedbytheCOconversionthe higher the CO conversion the higher the C5+ selectivity(SC5+)andasaconsequencetheselectivitytoCH4andC2-C4aredecreasedTheselectivity toCH4andC2-C4werehigher for theMEcatalystduringbothperiodsthismightbeattributedtotwofactslowCo0formationintheCoZr-Al2O3 (ME)catalystandthesmallpore sizeof thecarrier around4nm leading to internalmasstransferlimitationsfavoringthefasterH2 diffusionduetoitssmallersizecomparedtotheCOmoleculewhichdiffusesmoreslowlyThisledtohigherH2COratioswithinthecatalystparticlesthanatthepelletsurface

ConclusionForthefirsttimeZr-Aloxidesnanoparticlesweresynthesizedbythewater-in-oilmicroemulsionmethodThematerialpresentedahighZrdispersioninaluminaanditwashighlyhomogeneouswith uniform particle size narrow pore size distribution andhighsurfaceareaThismaterialwasusedascobaltsupportandcomparedwithsimilarmaterialpreparedbyZr impregnatedoncommercial alumina The presence of ZrO2-islands on aluminafavoredthedispersionanddegreeofreductionofcobaltwhile

the high Zr dispersion in the Zr-Al2O3 (ME) material hinderedZrO2crystallizationThisproducedamoreamorphousmaterialleading to ahigherdegreeof CoAl2O4 formationand thereforeincreased selectivity tomethaneand short-chainhydrocarbonsC2-C4ThecatalyticactivityandSC5+isfavouredbytheCoZr-Al2O3

(IM)catalystTheseresultsareattributedtothecatalystporosityandhigherCo0availabilityonthesurfaceHowevereven if thecobaltonZr-Al2O3nanoparticles(preparedbywater-in-oilmicroemulsion)isnotthebestcatalystforCOhydrogenationreactionwhen a high C5+ selectivity is desired the material has verygoodpropertiestobeconsideredforotherapplicationssuchasbasedmaterial in three-way-catalyst or as catalyst support forothercatalyticreactionlikehydrodesulphurizationortostabilizealuminaphaseswhenitisusedathightemperatures

Acknowledgments SwedishInternationalDevelopmentCooperationAgency(SIDA)NanoandesnetworkandEuropeanprojectCOSTActionCM1101forfinancialsupportSpecialthankstoDrEmanuelaNegro(DeftUniversityofTechnology)EdgarCardenas(LulearingUniversity)andCesarLeyvaPorras(CIMAVSC)formeasurementsofTEMSEMandHRTEMSTEM

0 200 400 600 800 1000 1200

804CoZr-Al2O3(ME)

CoZr-Al2O3(IM)

722

466

918

742608

350

252

925734

383

318CoAl2O3

Inte

nsity

(au

)

Temperature [degC]400 600 800 1000 1200

968754

428

989749

625

838744

606

CoAl2O3

CoZr-Al2O3 (IM)

CoZr-Al2O3 (ME)

Inte

nsity

(au

)

Temperature [degC]

Figure 5 TPRprofileforthefreshcatalyst(left)andafteractivationat350degCfor16h(right)

GHSV (Ncm3(gh-1) Catalysts XCO () SCH4a

() SC2-C4a () SC5+

a () SCO2 ()

6000 CoAl2O3 65 120 120 750 101500 CoAl2O3 280 85 110 800 056000 CoZr-Al2O3(IM) 120 100 78 810 122350 CoZr-Al2O3(IM) 310 76 60 860 046000 CoZr-Al2O3(ME) 40 200 160 610 301000 CoZr-Al2O3(ME) 270 170 150 670 10

Table 4COconversionlevelsandselectivitydataforthedifferentcatalystsa SelectivitiesareCO2-free

8

ARCHIVOS DE MEDICINAISSN 1698-9465

2017Vol 2 No 2 9

This article is available in httpwwwimedpubcomsynthesis-and-catalysis-open-access

Synthesis and Catalysis Open AccessISSN 2574-0431

References1 Thomas JM (2009) Handbook of Heterogeneous Catalysis In

Angewandte Chemie International Edition Wiley-VCH VerlagWeinheim483390-3391

2 DryME(2002)Thefischerndashtropschprocess1950ndash2000CatalToday71227-241

3 SuaacuterezPRLopezLBarrientosJPardoFBoutonnetMetal(2015)Catalyticconversionofbiomass-derivedsynthesisgastofuels

4 VandeLoosdrechtJBotesFGCiobicaIMFerreiraACGibsonPetal(2013)FischerndashTropschSynthesisCatalystsandChemistryElsevierAmsterdampp525-557

5 GrenobleDCEstadtMMOllisDF(1981)Thechemistryandcatalysisofthewatergasshiftreaction1ThekineticsoversupportedmetalcatalystsJCatal6790-102

6 Tsakoumis NE Roslashnning M Borg Oslash Rytter E Holmen A (2010)Deactivation of cobalt based FischerndashTropsch catalysts A reviewCatalToday154162-182

7 BorgOslashEriSBlekkanEAStorsaeligterSWigumHetal(2007)FischerndashTropschsynthesisoverγ-alumina-supportedcobaltcatalystsEffectofsupportvariablesJCatal24889-100

8 MoradiGRBasirMMTaebAKiennemannA(2003)PromotionofCoSiO2FischerndashTropschcatalystswithzirconiumCatalCommun427-32

9 MiyazawaTHanaokaTShimuraKHirataS(2014)FischerndashTropschsynthesis over aCoSiO2 catalystmodifiedwithMn- andZrunderpracticalconditionsCatalCommun5736-39

10 Miyazawa T Hanaoka T Shimura K Hirata S (2013) Mn and Zrmodified CoSiO2 catalysts development in slurry-phase FischerndashTropschsynthesisAppliedCatalysisAGeneral46747-54

11 LiuYChenJFangKWangYSunY(2007)Alargepore-sizemesoporouszirconiasupportedcobaltcatalystwithgoodperformanceinFischerndashTropschsynthesisCatalCommun8945-949

12 Li ZWu J Yu JHanDWuL et al (2016)Effectof incorporationmanner of Zr on the CoSBA-15 catalyst for the FischerndashTropschsynthesisJMolCatalAChem424384-392

13 ShimuraKMiyazawaTHanaokaTHirataS(2015)FischerndashTropschsynthesisoveraluminasupportedcobaltcatalystEffectofpromoteradditionAppliedCatalysisAGeneral4941-11

14 Enache DI Roy-Auberger M Revel R (2014) Differences in thecharacteristics and catalytic properties of cobalt-based FischerndashTropsch catalysts supported on zirconia and alumina AppliedCatalysisAGeneral26851-60

15 RohrF LindvaringgOAHolmenABlekkanEA (2000)FischerndashTropschsynthesis over cobalt catalysts supported on zirconia-modifiedaluminaCatalToday58247-254

16 Jongsomjit B Panpranot J Goodwin JG (2003) Effect of zirconia-modifiedaluminaonthepropertiesofCoγ-Al2O3catalysts JCatal21566-77

17 Jacobs G Das TK Zhang Y Li J Racoillet G et al (2002) FischerndashTropsch synthesis support loading and promoter effects on thereducibility of cobalt catalysts Applied Catalysis A General 233263-281

18 Boutonnet M Marinas A Montes V Suaacuterez-Paris R Saacutenchez-Domınguez M (2016) Nanocatalysts Synthesis in Nanostructured

Liquid Media and Their Application in Energy and Production ofChemicalsinNanocolloidsElsevierAmsterdampp211-246

19 KombaiahKVijayaJJKennedyLJBououdinaMAl-LohedanHAetal(2017)StudiesonOpuntiadileniihawmediatedmultifunctionalZnFe2O4nanoparticlesOpticalmagneticandcatalyticapplicationsMaterChemPhys194153-164

20 Singh AK (2016) Structure Synthesis and Application ofNanoparticlesinEngineeredNanoparticlesAcademicPressBostonpp19-76

21 Eriksson S Nyleacuten U Rojas S Boutonnet M (2004) Preparationof catalysts from microemulsions and their applications inheterogeneouscatalysisApplCatalA265207-219

22 Pardo-Tarifa F Cabrera S Sanchez-Dominguez M Boutonnet M(2017) Ce-promoted CoAl 2 O 3 catalysts for Fischer-TropschsynthesisIntJHydrogenEnergy429754-9765

23 BoutonnetMSanchez-DominguezM(2017)MicroemulsiondropletstocatalyticallyactivenanoparticlesHowtheapplicationofcolloidaltools in catalysis aims towell design and efficient catalysts CatalToday28589-103

24 MisonoM(2013)ChemistryandCatalysisofMixedOxidesStudSurfSciCatal25-65

25 Sprague MJ (1985) Characterization of heterogeneous catalystsChemieIngenieurTechnik57430-430

26 LemaitreJLDelannayPGF(1984)CharacterizationofHeterogeneousCatalystsDenkerNewYork299-365

27 Schanke D Vada S Blekkan EA Hilmen AM Hoff A et al (1995)StudyofPt-promotedcobaltCOhydrogenationcatalystsJCatal15685-95

28 LoumlgdbergSLualdiMJaumlraringsSWalmsleyJCBlekkanEAetal(2010)Ontheselectivityofcobalt-basedFischerndashTropschcatalystsevidenceforacommonprecursorformethaneandlong-chainhydrocarbonsJCatal27484-98

29 ReuelRCBartholomewCH(1984)ThestoichiometriesofH2andCOadsorptionsoncobaltEffectsofsupportandpreparationJCatal8563-77

30 Jones RD Bartholomew CH (1988) Improved flow technique formeasurementofhydrogen chemisorptiononmetal catalystsApplCatal3977-88

31 Bhatia S Beltramini J Do DD (1990) Temperature programmedanalysisanditsapplicationsincatalyticsystemsCatalToday7309-438

32 Lualdi M Loumlgdberg S Regali F Boutonnet M Jaumlrarings S (2011)Investigation of mixtures of a Co-based catalyst and a Cu-basedcatalyst for the FischerndashTropsch synthesis with bio-syngas theimportanceofindigenouswaterTopCatal54977-985

33 Storsaeligter S Borg Oslash Blekkan EA Holmen A (2005) Study of theeffectofwateronFischerndashTropschsynthesisoversupportedcobaltcatalystsJCatal231405-419

34 Lualdi M (2012) Fischer-Tropsch Synthesis over Cobalt-basedCatalystsforBTLApplications

35 BoutonnetMLoumlgdbergSSvenssonEE(2008)RecentdevelopmentsintheapplicationofnanoparticlespreparedfromwomicroemulsionsinheterogeneouscatalysisCurrOpinColloidInterfaceSci13270-286

36 ChandradassJKimKH(2009)Effectofacidityonthecitrate-nitrate

9

ARCHIVOS DE MEDICINAISSN 1698-9465

2017Vol 2 No 2 9

copy Under License of Creative Commons Attribution 30 License

Synthesis and Catalysis Open AccessISSN 2574-0431

combustion synthesis of alumina-zirconia composite powderMetMaterInt151039-1043

37 Baudiacuten C (2014) Processing of Alumina and CorrespondingCompositesComprehensiveHardMaterials3172

38 ThommesMKanekoKNeimarkAVOlivier JP Rodriguez-ReinosoFetal(2015)Physisorptionofgaseswithspecialreferencetotheevaluation of surface area and pore size distribution Pure ApplChem871051-1069

39 MartiacutenezAPrietoGRollaacutenJ(2009)Nanofibrousγ-Al2O3assupportforCo-basedFischerndashTropschcatalystsponderingtherelevanceofdiffusionalanddispersioneffectsoncatalyticperformance JCatal263292-305

40 Liu C Li J Zhang Y Chen S Zhu J et al (2012) FischerndashTropschsynthesisovercobaltcatalystssupportedonnanostructuredaluminawithvariousmorphologiesJMolCatalAChem363335-342

41 CastnerDGWatsonPRChanIY(1990)X-rayabsorptionspectroscopy

X-rayphotoelectronspectroscopyandanalyticalelectronmicroscopystudiesofcobaltcatalysts2HydrogenreductionpropertiesJPhysChem94819-828

42 OslashyvindBMagnusRSOslashlviSAndersH(2007)Identificationofcobaltspecies during temperature programmed reduction of Fischer-TropschcatalystsStudiesinSurfaceScienceandCatalysis163255-272

43 Topsoslashe NY Topsoslashe H (1982) Adsorption studies onhydrodesulfurization catalysts I Infrared and volumetric study ofNOadsorptiononalumina-supportedCoMoandCo-MocatalystsintheircalcinedstateJCatal75354-374

44 SimionatoMAssafEM(2003)Preparationandcharacterizationofalumina-supportedCoandAgCocatalystsMaterRes6535-539

45 VandeLoosdrechtJVanderHaarMVanderKraanAMVanDillenAJGeusJW(1997)PreparationandpropertiesofsupportedcobaltcatalystsforFischer-TropschsynthesisApplCatalA150365-376

Page 5: Synthesis and Characterization of Novel Zr-Al2O3 ... Prepared2 by Microemulsion Method and Its Use as Cobalt Catalyst Support for the CO Hydrogenation Reaction. Synth Catal. 2017,

5

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H2-Temperature programmed reduction A typical TPR profileforallthecatalystsisshowninFigure 5IngeneralthefirsttwopeakscorrespondtothereductionofCo3O4+H2rarr3CoO+H2O [41]and3CoO+3H2rarr3Co0+3H2O[42]Thepeakaround700degCis attributed toCo3AlO6 (Co3O4-AlO2) andorCoO-Al2O3and thepeakat900degCcorrespondstoCoAl2O4[43-45]

Co3O4 in CoZr-Al2O3(ME) was harder to reduce as aconsequence the reduction temperature was shifted towardshigher temperature compared to the other catalysts The lackof crystallinity in the ME carrier favored the cobalt-aluminateformationandalsoitsreductiontemperature

TheTPRforCoZr-Al2O3(IM)presentssimilarpeaksasforCoAl2O3 withthedifferencethatthereductiontemperaturewaslowerbyabout 50degC In addition an extra H2 uptakewas seen at 608degCwhichcancorrespondtothepartialreductionofZrTheamountof cobalt aluminate specieswasdecreasedcomparedwithCoAl2O3attributedtothepresenceofZrCoAl2O4(spinel)wasnotdetected by the XRD technique since its diffractogram peaksoverlapstheCo3O4peaks

Additionally TPR experiments (Figure 5 right)were performedafter the catalyst activation in order to identify the unreducedcobalt amount and consequently the degree of reduction(DOR) (ie from 350 to 930degC in H2) Co3O4 in CoZr-Al2O3(IM)iscompletelyreducedaftercatalystactivationwithaDORof47whiletheDORforCoAl2O3andforZr-Al2O3(ME)is30and11 respectively (Table 3 and Figure 5) Thereafter it can beconcludedthatthepresenceofZrinislandsasisthecaseofCoZr-Al2O3(IM)decreasethecobalt-aluminainteractionsfavoringinthisway amoremetallic formationwhich is required for a COhydrogenationreaction

Interestingtonoteinallthecatalysts(Figure 5 right)isthattheunreducedcobaltspecies(peaksaround700and900degC)shiftedthe reduction temperature to higher temperatures comparedwiththefirstTPRanalysis(Figure 5 left)Theexplanationgivenisthatduringcatalystsactivationtheremainingunreduced-cobaltintheformofCodeg interactswithwater(producedbythemetalreduction) to form Co-aluminate which is reduced at a highertemperature[15]

Table 3 presentsthedispersionofmetalliccobaltCodegcalculatedbyH2chemisorption(illustratedinexperimentalpart)TheresultsshowthatCodegdispersionisquitesimilar inCoZr-Al2O3(IM) andCoZr-Al2O3(ME) These results compared with CoAl2O3 arehighersoit isconcludedthatZrfavorsthedispersionofcobaltinaluminasupportInadditionthemeasuredCodegparticlesizebythistechniqueandbyTEMishigherthanthecalculatedfromtheScherrerequation fromwhich it canbeconcluded thatduringcatalystactivationthemetallicparticlesaresinteredThiseffectishigher inCoZr-Al2O3(ME)andoneof theexplanationsmightbeduetothetexturalporosityandthelackofstructuralporositywhichmakesthecobalt-sinteringeasier

Catalytic testComparingCOconversionsforallthecatalystsafter25hofsyngasstream(H2 CO=21)(Table 4)thecatalystactivitydecreasesinthefollowingorderCoZr-Al2O3(IM)gtCoAl2O3gtCoZr-Al2O3(ME)The

00 02 04 06 08 10

100

200

300

400

500

Volum

e ad

sorb

ed [c

m3 g

STP

]

Relative Pressure (PP0)

CoZr-Al2O3(IM)

0 20 40 60 80 100 120 140 160

000

002

004

006

008

010

012

Pore

vol

ume

volu

me

[cm

3 g]

Pore diameter [nm]

00 02 04 06 08 10

100

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400

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600

Relative Pressure (PP0)

CoAl2O3

Volum

e ad

sorb

ed [c

m3 g

STP

]

0 20 40 60 80 100 120 140 160

000

002

004

006

008

010

012

Pore diameter [nm]

Pore

volum

e volu

me [c

m3 g]

-04 -02 00 02 04 06 08 10

50

100

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CoZr-Al2O3(ME)

Relative Pressure (PP0)

Volum

e ad

sorb

ed [c

m3 g

STP

]

0 5 10 15 20

000

002

004

006

008

010

012

Pore

volu

me v

olum

e [cm

3 g]

Pore diameter [nm]

Figure 2 TheN2 adsorption-desorption isotherms and pore sizedistributioncurvesforthecobaltcatalysts

CoZr-Al2O3(ME) shows a homogeneous material formed byagglomerated nanoparticles CoZr-Al2O3(ME) shows carrierparticlesizesbetween4-7nmandCo3O4cubiccrystals(Figure 4a)STEM-EDXmappingresultsshowahomogeneousdistributionofZronCoZr-Al2O3(ME) (Figure 4a)ThispicturedemonstrateshowtheMEtechniquecanbeappliedforthesynthesisofhighlydisperseoxidepromoteronacarrierTheZrdispersiononaluminainCoZr-Al2O3(IM)(Figure 4b)waslowerformingZr-richislandsontheAl2O3 surfaceFurthermorethecobaltdepositionseemstobebetterintheMEmaterialthanintheZr-impregnatedmaterial

6

ARCHIVOS DE MEDICINAISSN 1698-9465

2017Vol 2 No 2 9

This article is available in httpwwwimedpubcomsynthesis-and-catalysis-open-access

Synthesis and Catalysis Open AccessISSN 2574-0431

Figure 3 SEMpicturesforthecarrierandthecobaltcatalysts

a)CoZr-Al2O3(ME) b) CoZr-Al2O3(IM )

20 nm 300 nm

600 nm

Zr Zr

Al Co Co Al

300 nm

4 nm

Figure 4 RepresentativeSTEM-EDXelementalmappingfora)CoZr-Al2O3(ME)andb)CoZr-Al2O3(IM)

7

ARCHIVOS DE MEDICINAISSN 1698-9465

2017Vol 2 No 2 9

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resultsarerelatedtothehighertheDOR(degreeofreductionofCo)thehighertheCOconversioninperiodone(Table 3)

InallthecasestheselectivityisaffectedbytheCOconversionthe higher the CO conversion the higher the C5+ selectivity(SC5+)andasaconsequencetheselectivitytoCH4andC2-C4aredecreasedTheselectivity toCH4andC2-C4werehigher for theMEcatalystduringbothperiodsthismightbeattributedtotwofactslowCo0formationintheCoZr-Al2O3 (ME)catalystandthesmallpore sizeof thecarrier around4nm leading to internalmasstransferlimitationsfavoringthefasterH2 diffusionduetoitssmallersizecomparedtotheCOmoleculewhichdiffusesmoreslowlyThisledtohigherH2COratioswithinthecatalystparticlesthanatthepelletsurface

ConclusionForthefirsttimeZr-Aloxidesnanoparticlesweresynthesizedbythewater-in-oilmicroemulsionmethodThematerialpresentedahighZrdispersioninaluminaanditwashighlyhomogeneouswith uniform particle size narrow pore size distribution andhighsurfaceareaThismaterialwasusedascobaltsupportandcomparedwithsimilarmaterialpreparedbyZr impregnatedoncommercial alumina The presence of ZrO2-islands on aluminafavoredthedispersionanddegreeofreductionofcobaltwhile

the high Zr dispersion in the Zr-Al2O3 (ME) material hinderedZrO2crystallizationThisproducedamoreamorphousmaterialleading to ahigherdegreeof CoAl2O4 formationand thereforeincreased selectivity tomethaneand short-chainhydrocarbonsC2-C4ThecatalyticactivityandSC5+isfavouredbytheCoZr-Al2O3

(IM)catalystTheseresultsareattributedtothecatalystporosityandhigherCo0availabilityonthesurfaceHowevereven if thecobaltonZr-Al2O3nanoparticles(preparedbywater-in-oilmicroemulsion)isnotthebestcatalystforCOhydrogenationreactionwhen a high C5+ selectivity is desired the material has verygoodpropertiestobeconsideredforotherapplicationssuchasbasedmaterial in three-way-catalyst or as catalyst support forothercatalyticreactionlikehydrodesulphurizationortostabilizealuminaphaseswhenitisusedathightemperatures

Acknowledgments SwedishInternationalDevelopmentCooperationAgency(SIDA)NanoandesnetworkandEuropeanprojectCOSTActionCM1101forfinancialsupportSpecialthankstoDrEmanuelaNegro(DeftUniversityofTechnology)EdgarCardenas(LulearingUniversity)andCesarLeyvaPorras(CIMAVSC)formeasurementsofTEMSEMandHRTEMSTEM

0 200 400 600 800 1000 1200

804CoZr-Al2O3(ME)

CoZr-Al2O3(IM)

722

466

918

742608

350

252

925734

383

318CoAl2O3

Inte

nsity

(au

)

Temperature [degC]400 600 800 1000 1200

968754

428

989749

625

838744

606

CoAl2O3

CoZr-Al2O3 (IM)

CoZr-Al2O3 (ME)

Inte

nsity

(au

)

Temperature [degC]

Figure 5 TPRprofileforthefreshcatalyst(left)andafteractivationat350degCfor16h(right)

GHSV (Ncm3(gh-1) Catalysts XCO () SCH4a

() SC2-C4a () SC5+

a () SCO2 ()

6000 CoAl2O3 65 120 120 750 101500 CoAl2O3 280 85 110 800 056000 CoZr-Al2O3(IM) 120 100 78 810 122350 CoZr-Al2O3(IM) 310 76 60 860 046000 CoZr-Al2O3(ME) 40 200 160 610 301000 CoZr-Al2O3(ME) 270 170 150 670 10

Table 4COconversionlevelsandselectivitydataforthedifferentcatalystsa SelectivitiesareCO2-free

8

ARCHIVOS DE MEDICINAISSN 1698-9465

2017Vol 2 No 2 9

This article is available in httpwwwimedpubcomsynthesis-and-catalysis-open-access

Synthesis and Catalysis Open AccessISSN 2574-0431

References1 Thomas JM (2009) Handbook of Heterogeneous Catalysis In

Angewandte Chemie International Edition Wiley-VCH VerlagWeinheim483390-3391

2 DryME(2002)Thefischerndashtropschprocess1950ndash2000CatalToday71227-241

3 SuaacuterezPRLopezLBarrientosJPardoFBoutonnetMetal(2015)Catalyticconversionofbiomass-derivedsynthesisgastofuels

4 VandeLoosdrechtJBotesFGCiobicaIMFerreiraACGibsonPetal(2013)FischerndashTropschSynthesisCatalystsandChemistryElsevierAmsterdampp525-557

5 GrenobleDCEstadtMMOllisDF(1981)Thechemistryandcatalysisofthewatergasshiftreaction1ThekineticsoversupportedmetalcatalystsJCatal6790-102

6 Tsakoumis NE Roslashnning M Borg Oslash Rytter E Holmen A (2010)Deactivation of cobalt based FischerndashTropsch catalysts A reviewCatalToday154162-182

7 BorgOslashEriSBlekkanEAStorsaeligterSWigumHetal(2007)FischerndashTropschsynthesisoverγ-alumina-supportedcobaltcatalystsEffectofsupportvariablesJCatal24889-100

8 MoradiGRBasirMMTaebAKiennemannA(2003)PromotionofCoSiO2FischerndashTropschcatalystswithzirconiumCatalCommun427-32

9 MiyazawaTHanaokaTShimuraKHirataS(2014)FischerndashTropschsynthesis over aCoSiO2 catalystmodifiedwithMn- andZrunderpracticalconditionsCatalCommun5736-39

10 Miyazawa T Hanaoka T Shimura K Hirata S (2013) Mn and Zrmodified CoSiO2 catalysts development in slurry-phase FischerndashTropschsynthesisAppliedCatalysisAGeneral46747-54

11 LiuYChenJFangKWangYSunY(2007)Alargepore-sizemesoporouszirconiasupportedcobaltcatalystwithgoodperformanceinFischerndashTropschsynthesisCatalCommun8945-949

12 Li ZWu J Yu JHanDWuL et al (2016)Effectof incorporationmanner of Zr on the CoSBA-15 catalyst for the FischerndashTropschsynthesisJMolCatalAChem424384-392

13 ShimuraKMiyazawaTHanaokaTHirataS(2015)FischerndashTropschsynthesisoveraluminasupportedcobaltcatalystEffectofpromoteradditionAppliedCatalysisAGeneral4941-11

14 Enache DI Roy-Auberger M Revel R (2014) Differences in thecharacteristics and catalytic properties of cobalt-based FischerndashTropsch catalysts supported on zirconia and alumina AppliedCatalysisAGeneral26851-60

15 RohrF LindvaringgOAHolmenABlekkanEA (2000)FischerndashTropschsynthesis over cobalt catalysts supported on zirconia-modifiedaluminaCatalToday58247-254

16 Jongsomjit B Panpranot J Goodwin JG (2003) Effect of zirconia-modifiedaluminaonthepropertiesofCoγ-Al2O3catalysts JCatal21566-77

17 Jacobs G Das TK Zhang Y Li J Racoillet G et al (2002) FischerndashTropsch synthesis support loading and promoter effects on thereducibility of cobalt catalysts Applied Catalysis A General 233263-281

18 Boutonnet M Marinas A Montes V Suaacuterez-Paris R Saacutenchez-Domınguez M (2016) Nanocatalysts Synthesis in Nanostructured

Liquid Media and Their Application in Energy and Production ofChemicalsinNanocolloidsElsevierAmsterdampp211-246

19 KombaiahKVijayaJJKennedyLJBououdinaMAl-LohedanHAetal(2017)StudiesonOpuntiadileniihawmediatedmultifunctionalZnFe2O4nanoparticlesOpticalmagneticandcatalyticapplicationsMaterChemPhys194153-164

20 Singh AK (2016) Structure Synthesis and Application ofNanoparticlesinEngineeredNanoparticlesAcademicPressBostonpp19-76

21 Eriksson S Nyleacuten U Rojas S Boutonnet M (2004) Preparationof catalysts from microemulsions and their applications inheterogeneouscatalysisApplCatalA265207-219

22 Pardo-Tarifa F Cabrera S Sanchez-Dominguez M Boutonnet M(2017) Ce-promoted CoAl 2 O 3 catalysts for Fischer-TropschsynthesisIntJHydrogenEnergy429754-9765

23 BoutonnetMSanchez-DominguezM(2017)MicroemulsiondropletstocatalyticallyactivenanoparticlesHowtheapplicationofcolloidaltools in catalysis aims towell design and efficient catalysts CatalToday28589-103

24 MisonoM(2013)ChemistryandCatalysisofMixedOxidesStudSurfSciCatal25-65

25 Sprague MJ (1985) Characterization of heterogeneous catalystsChemieIngenieurTechnik57430-430

26 LemaitreJLDelannayPGF(1984)CharacterizationofHeterogeneousCatalystsDenkerNewYork299-365

27 Schanke D Vada S Blekkan EA Hilmen AM Hoff A et al (1995)StudyofPt-promotedcobaltCOhydrogenationcatalystsJCatal15685-95

28 LoumlgdbergSLualdiMJaumlraringsSWalmsleyJCBlekkanEAetal(2010)Ontheselectivityofcobalt-basedFischerndashTropschcatalystsevidenceforacommonprecursorformethaneandlong-chainhydrocarbonsJCatal27484-98

29 ReuelRCBartholomewCH(1984)ThestoichiometriesofH2andCOadsorptionsoncobaltEffectsofsupportandpreparationJCatal8563-77

30 Jones RD Bartholomew CH (1988) Improved flow technique formeasurementofhydrogen chemisorptiononmetal catalystsApplCatal3977-88

31 Bhatia S Beltramini J Do DD (1990) Temperature programmedanalysisanditsapplicationsincatalyticsystemsCatalToday7309-438

32 Lualdi M Loumlgdberg S Regali F Boutonnet M Jaumlrarings S (2011)Investigation of mixtures of a Co-based catalyst and a Cu-basedcatalyst for the FischerndashTropsch synthesis with bio-syngas theimportanceofindigenouswaterTopCatal54977-985

33 Storsaeligter S Borg Oslash Blekkan EA Holmen A (2005) Study of theeffectofwateronFischerndashTropschsynthesisoversupportedcobaltcatalystsJCatal231405-419

34 Lualdi M (2012) Fischer-Tropsch Synthesis over Cobalt-basedCatalystsforBTLApplications

35 BoutonnetMLoumlgdbergSSvenssonEE(2008)RecentdevelopmentsintheapplicationofnanoparticlespreparedfromwomicroemulsionsinheterogeneouscatalysisCurrOpinColloidInterfaceSci13270-286

36 ChandradassJKimKH(2009)Effectofacidityonthecitrate-nitrate

9

ARCHIVOS DE MEDICINAISSN 1698-9465

2017Vol 2 No 2 9

copy Under License of Creative Commons Attribution 30 License

Synthesis and Catalysis Open AccessISSN 2574-0431

combustion synthesis of alumina-zirconia composite powderMetMaterInt151039-1043

37 Baudiacuten C (2014) Processing of Alumina and CorrespondingCompositesComprehensiveHardMaterials3172

38 ThommesMKanekoKNeimarkAVOlivier JP Rodriguez-ReinosoFetal(2015)Physisorptionofgaseswithspecialreferencetotheevaluation of surface area and pore size distribution Pure ApplChem871051-1069

39 MartiacutenezAPrietoGRollaacutenJ(2009)Nanofibrousγ-Al2O3assupportforCo-basedFischerndashTropschcatalystsponderingtherelevanceofdiffusionalanddispersioneffectsoncatalyticperformance JCatal263292-305

40 Liu C Li J Zhang Y Chen S Zhu J et al (2012) FischerndashTropschsynthesisovercobaltcatalystssupportedonnanostructuredaluminawithvariousmorphologiesJMolCatalAChem363335-342

41 CastnerDGWatsonPRChanIY(1990)X-rayabsorptionspectroscopy

X-rayphotoelectronspectroscopyandanalyticalelectronmicroscopystudiesofcobaltcatalysts2HydrogenreductionpropertiesJPhysChem94819-828

42 OslashyvindBMagnusRSOslashlviSAndersH(2007)Identificationofcobaltspecies during temperature programmed reduction of Fischer-TropschcatalystsStudiesinSurfaceScienceandCatalysis163255-272

43 Topsoslashe NY Topsoslashe H (1982) Adsorption studies onhydrodesulfurization catalysts I Infrared and volumetric study ofNOadsorptiononalumina-supportedCoMoandCo-MocatalystsintheircalcinedstateJCatal75354-374

44 SimionatoMAssafEM(2003)Preparationandcharacterizationofalumina-supportedCoandAgCocatalystsMaterRes6535-539

45 VandeLoosdrechtJVanderHaarMVanderKraanAMVanDillenAJGeusJW(1997)PreparationandpropertiesofsupportedcobaltcatalystsforFischer-TropschsynthesisApplCatalA150365-376

Page 6: Synthesis and Characterization of Novel Zr-Al2O3 ... Prepared2 by Microemulsion Method and Its Use as Cobalt Catalyst Support for the CO Hydrogenation Reaction. Synth Catal. 2017,

6

ARCHIVOS DE MEDICINAISSN 1698-9465

2017Vol 2 No 2 9

This article is available in httpwwwimedpubcomsynthesis-and-catalysis-open-access

Synthesis and Catalysis Open AccessISSN 2574-0431

Figure 3 SEMpicturesforthecarrierandthecobaltcatalysts

a)CoZr-Al2O3(ME) b) CoZr-Al2O3(IM )

20 nm 300 nm

600 nm

Zr Zr

Al Co Co Al

300 nm

4 nm

Figure 4 RepresentativeSTEM-EDXelementalmappingfora)CoZr-Al2O3(ME)andb)CoZr-Al2O3(IM)

7

ARCHIVOS DE MEDICINAISSN 1698-9465

2017Vol 2 No 2 9

copy Under License of Creative Commons Attribution 30 License

Synthesis and Catalysis Open AccessISSN 2574-0431

resultsarerelatedtothehighertheDOR(degreeofreductionofCo)thehighertheCOconversioninperiodone(Table 3)

InallthecasestheselectivityisaffectedbytheCOconversionthe higher the CO conversion the higher the C5+ selectivity(SC5+)andasaconsequencetheselectivitytoCH4andC2-C4aredecreasedTheselectivity toCH4andC2-C4werehigher for theMEcatalystduringbothperiodsthismightbeattributedtotwofactslowCo0formationintheCoZr-Al2O3 (ME)catalystandthesmallpore sizeof thecarrier around4nm leading to internalmasstransferlimitationsfavoringthefasterH2 diffusionduetoitssmallersizecomparedtotheCOmoleculewhichdiffusesmoreslowlyThisledtohigherH2COratioswithinthecatalystparticlesthanatthepelletsurface

ConclusionForthefirsttimeZr-Aloxidesnanoparticlesweresynthesizedbythewater-in-oilmicroemulsionmethodThematerialpresentedahighZrdispersioninaluminaanditwashighlyhomogeneouswith uniform particle size narrow pore size distribution andhighsurfaceareaThismaterialwasusedascobaltsupportandcomparedwithsimilarmaterialpreparedbyZr impregnatedoncommercial alumina The presence of ZrO2-islands on aluminafavoredthedispersionanddegreeofreductionofcobaltwhile

the high Zr dispersion in the Zr-Al2O3 (ME) material hinderedZrO2crystallizationThisproducedamoreamorphousmaterialleading to ahigherdegreeof CoAl2O4 formationand thereforeincreased selectivity tomethaneand short-chainhydrocarbonsC2-C4ThecatalyticactivityandSC5+isfavouredbytheCoZr-Al2O3

(IM)catalystTheseresultsareattributedtothecatalystporosityandhigherCo0availabilityonthesurfaceHowevereven if thecobaltonZr-Al2O3nanoparticles(preparedbywater-in-oilmicroemulsion)isnotthebestcatalystforCOhydrogenationreactionwhen a high C5+ selectivity is desired the material has verygoodpropertiestobeconsideredforotherapplicationssuchasbasedmaterial in three-way-catalyst or as catalyst support forothercatalyticreactionlikehydrodesulphurizationortostabilizealuminaphaseswhenitisusedathightemperatures

Acknowledgments SwedishInternationalDevelopmentCooperationAgency(SIDA)NanoandesnetworkandEuropeanprojectCOSTActionCM1101forfinancialsupportSpecialthankstoDrEmanuelaNegro(DeftUniversityofTechnology)EdgarCardenas(LulearingUniversity)andCesarLeyvaPorras(CIMAVSC)formeasurementsofTEMSEMandHRTEMSTEM

0 200 400 600 800 1000 1200

804CoZr-Al2O3(ME)

CoZr-Al2O3(IM)

722

466

918

742608

350

252

925734

383

318CoAl2O3

Inte

nsity

(au

)

Temperature [degC]400 600 800 1000 1200

968754

428

989749

625

838744

606

CoAl2O3

CoZr-Al2O3 (IM)

CoZr-Al2O3 (ME)

Inte

nsity

(au

)

Temperature [degC]

Figure 5 TPRprofileforthefreshcatalyst(left)andafteractivationat350degCfor16h(right)

GHSV (Ncm3(gh-1) Catalysts XCO () SCH4a

() SC2-C4a () SC5+

a () SCO2 ()

6000 CoAl2O3 65 120 120 750 101500 CoAl2O3 280 85 110 800 056000 CoZr-Al2O3(IM) 120 100 78 810 122350 CoZr-Al2O3(IM) 310 76 60 860 046000 CoZr-Al2O3(ME) 40 200 160 610 301000 CoZr-Al2O3(ME) 270 170 150 670 10

Table 4COconversionlevelsandselectivitydataforthedifferentcatalystsa SelectivitiesareCO2-free

8

ARCHIVOS DE MEDICINAISSN 1698-9465

2017Vol 2 No 2 9

This article is available in httpwwwimedpubcomsynthesis-and-catalysis-open-access

Synthesis and Catalysis Open AccessISSN 2574-0431

References1 Thomas JM (2009) Handbook of Heterogeneous Catalysis In

Angewandte Chemie International Edition Wiley-VCH VerlagWeinheim483390-3391

2 DryME(2002)Thefischerndashtropschprocess1950ndash2000CatalToday71227-241

3 SuaacuterezPRLopezLBarrientosJPardoFBoutonnetMetal(2015)Catalyticconversionofbiomass-derivedsynthesisgastofuels

4 VandeLoosdrechtJBotesFGCiobicaIMFerreiraACGibsonPetal(2013)FischerndashTropschSynthesisCatalystsandChemistryElsevierAmsterdampp525-557

5 GrenobleDCEstadtMMOllisDF(1981)Thechemistryandcatalysisofthewatergasshiftreaction1ThekineticsoversupportedmetalcatalystsJCatal6790-102

6 Tsakoumis NE Roslashnning M Borg Oslash Rytter E Holmen A (2010)Deactivation of cobalt based FischerndashTropsch catalysts A reviewCatalToday154162-182

7 BorgOslashEriSBlekkanEAStorsaeligterSWigumHetal(2007)FischerndashTropschsynthesisoverγ-alumina-supportedcobaltcatalystsEffectofsupportvariablesJCatal24889-100

8 MoradiGRBasirMMTaebAKiennemannA(2003)PromotionofCoSiO2FischerndashTropschcatalystswithzirconiumCatalCommun427-32

9 MiyazawaTHanaokaTShimuraKHirataS(2014)FischerndashTropschsynthesis over aCoSiO2 catalystmodifiedwithMn- andZrunderpracticalconditionsCatalCommun5736-39

10 Miyazawa T Hanaoka T Shimura K Hirata S (2013) Mn and Zrmodified CoSiO2 catalysts development in slurry-phase FischerndashTropschsynthesisAppliedCatalysisAGeneral46747-54

11 LiuYChenJFangKWangYSunY(2007)Alargepore-sizemesoporouszirconiasupportedcobaltcatalystwithgoodperformanceinFischerndashTropschsynthesisCatalCommun8945-949

12 Li ZWu J Yu JHanDWuL et al (2016)Effectof incorporationmanner of Zr on the CoSBA-15 catalyst for the FischerndashTropschsynthesisJMolCatalAChem424384-392

13 ShimuraKMiyazawaTHanaokaTHirataS(2015)FischerndashTropschsynthesisoveraluminasupportedcobaltcatalystEffectofpromoteradditionAppliedCatalysisAGeneral4941-11

14 Enache DI Roy-Auberger M Revel R (2014) Differences in thecharacteristics and catalytic properties of cobalt-based FischerndashTropsch catalysts supported on zirconia and alumina AppliedCatalysisAGeneral26851-60

15 RohrF LindvaringgOAHolmenABlekkanEA (2000)FischerndashTropschsynthesis over cobalt catalysts supported on zirconia-modifiedaluminaCatalToday58247-254

16 Jongsomjit B Panpranot J Goodwin JG (2003) Effect of zirconia-modifiedaluminaonthepropertiesofCoγ-Al2O3catalysts JCatal21566-77

17 Jacobs G Das TK Zhang Y Li J Racoillet G et al (2002) FischerndashTropsch synthesis support loading and promoter effects on thereducibility of cobalt catalysts Applied Catalysis A General 233263-281

18 Boutonnet M Marinas A Montes V Suaacuterez-Paris R Saacutenchez-Domınguez M (2016) Nanocatalysts Synthesis in Nanostructured

Liquid Media and Their Application in Energy and Production ofChemicalsinNanocolloidsElsevierAmsterdampp211-246

19 KombaiahKVijayaJJKennedyLJBououdinaMAl-LohedanHAetal(2017)StudiesonOpuntiadileniihawmediatedmultifunctionalZnFe2O4nanoparticlesOpticalmagneticandcatalyticapplicationsMaterChemPhys194153-164

20 Singh AK (2016) Structure Synthesis and Application ofNanoparticlesinEngineeredNanoparticlesAcademicPressBostonpp19-76

21 Eriksson S Nyleacuten U Rojas S Boutonnet M (2004) Preparationof catalysts from microemulsions and their applications inheterogeneouscatalysisApplCatalA265207-219

22 Pardo-Tarifa F Cabrera S Sanchez-Dominguez M Boutonnet M(2017) Ce-promoted CoAl 2 O 3 catalysts for Fischer-TropschsynthesisIntJHydrogenEnergy429754-9765

23 BoutonnetMSanchez-DominguezM(2017)MicroemulsiondropletstocatalyticallyactivenanoparticlesHowtheapplicationofcolloidaltools in catalysis aims towell design and efficient catalysts CatalToday28589-103

24 MisonoM(2013)ChemistryandCatalysisofMixedOxidesStudSurfSciCatal25-65

25 Sprague MJ (1985) Characterization of heterogeneous catalystsChemieIngenieurTechnik57430-430

26 LemaitreJLDelannayPGF(1984)CharacterizationofHeterogeneousCatalystsDenkerNewYork299-365

27 Schanke D Vada S Blekkan EA Hilmen AM Hoff A et al (1995)StudyofPt-promotedcobaltCOhydrogenationcatalystsJCatal15685-95

28 LoumlgdbergSLualdiMJaumlraringsSWalmsleyJCBlekkanEAetal(2010)Ontheselectivityofcobalt-basedFischerndashTropschcatalystsevidenceforacommonprecursorformethaneandlong-chainhydrocarbonsJCatal27484-98

29 ReuelRCBartholomewCH(1984)ThestoichiometriesofH2andCOadsorptionsoncobaltEffectsofsupportandpreparationJCatal8563-77

30 Jones RD Bartholomew CH (1988) Improved flow technique formeasurementofhydrogen chemisorptiononmetal catalystsApplCatal3977-88

31 Bhatia S Beltramini J Do DD (1990) Temperature programmedanalysisanditsapplicationsincatalyticsystemsCatalToday7309-438

32 Lualdi M Loumlgdberg S Regali F Boutonnet M Jaumlrarings S (2011)Investigation of mixtures of a Co-based catalyst and a Cu-basedcatalyst for the FischerndashTropsch synthesis with bio-syngas theimportanceofindigenouswaterTopCatal54977-985

33 Storsaeligter S Borg Oslash Blekkan EA Holmen A (2005) Study of theeffectofwateronFischerndashTropschsynthesisoversupportedcobaltcatalystsJCatal231405-419

34 Lualdi M (2012) Fischer-Tropsch Synthesis over Cobalt-basedCatalystsforBTLApplications

35 BoutonnetMLoumlgdbergSSvenssonEE(2008)RecentdevelopmentsintheapplicationofnanoparticlespreparedfromwomicroemulsionsinheterogeneouscatalysisCurrOpinColloidInterfaceSci13270-286

36 ChandradassJKimKH(2009)Effectofacidityonthecitrate-nitrate

9

ARCHIVOS DE MEDICINAISSN 1698-9465

2017Vol 2 No 2 9

copy Under License of Creative Commons Attribution 30 License

Synthesis and Catalysis Open AccessISSN 2574-0431

combustion synthesis of alumina-zirconia composite powderMetMaterInt151039-1043

37 Baudiacuten C (2014) Processing of Alumina and CorrespondingCompositesComprehensiveHardMaterials3172

38 ThommesMKanekoKNeimarkAVOlivier JP Rodriguez-ReinosoFetal(2015)Physisorptionofgaseswithspecialreferencetotheevaluation of surface area and pore size distribution Pure ApplChem871051-1069

39 MartiacutenezAPrietoGRollaacutenJ(2009)Nanofibrousγ-Al2O3assupportforCo-basedFischerndashTropschcatalystsponderingtherelevanceofdiffusionalanddispersioneffectsoncatalyticperformance JCatal263292-305

40 Liu C Li J Zhang Y Chen S Zhu J et al (2012) FischerndashTropschsynthesisovercobaltcatalystssupportedonnanostructuredaluminawithvariousmorphologiesJMolCatalAChem363335-342

41 CastnerDGWatsonPRChanIY(1990)X-rayabsorptionspectroscopy

X-rayphotoelectronspectroscopyandanalyticalelectronmicroscopystudiesofcobaltcatalysts2HydrogenreductionpropertiesJPhysChem94819-828

42 OslashyvindBMagnusRSOslashlviSAndersH(2007)Identificationofcobaltspecies during temperature programmed reduction of Fischer-TropschcatalystsStudiesinSurfaceScienceandCatalysis163255-272

43 Topsoslashe NY Topsoslashe H (1982) Adsorption studies onhydrodesulfurization catalysts I Infrared and volumetric study ofNOadsorptiononalumina-supportedCoMoandCo-MocatalystsintheircalcinedstateJCatal75354-374

44 SimionatoMAssafEM(2003)Preparationandcharacterizationofalumina-supportedCoandAgCocatalystsMaterRes6535-539

45 VandeLoosdrechtJVanderHaarMVanderKraanAMVanDillenAJGeusJW(1997)PreparationandpropertiesofsupportedcobaltcatalystsforFischer-TropschsynthesisApplCatalA150365-376

Page 7: Synthesis and Characterization of Novel Zr-Al2O3 ... Prepared2 by Microemulsion Method and Its Use as Cobalt Catalyst Support for the CO Hydrogenation Reaction. Synth Catal. 2017,

7

ARCHIVOS DE MEDICINAISSN 1698-9465

2017Vol 2 No 2 9

copy Under License of Creative Commons Attribution 30 License

Synthesis and Catalysis Open AccessISSN 2574-0431

resultsarerelatedtothehighertheDOR(degreeofreductionofCo)thehighertheCOconversioninperiodone(Table 3)

InallthecasestheselectivityisaffectedbytheCOconversionthe higher the CO conversion the higher the C5+ selectivity(SC5+)andasaconsequencetheselectivitytoCH4andC2-C4aredecreasedTheselectivity toCH4andC2-C4werehigher for theMEcatalystduringbothperiodsthismightbeattributedtotwofactslowCo0formationintheCoZr-Al2O3 (ME)catalystandthesmallpore sizeof thecarrier around4nm leading to internalmasstransferlimitationsfavoringthefasterH2 diffusionduetoitssmallersizecomparedtotheCOmoleculewhichdiffusesmoreslowlyThisledtohigherH2COratioswithinthecatalystparticlesthanatthepelletsurface

ConclusionForthefirsttimeZr-Aloxidesnanoparticlesweresynthesizedbythewater-in-oilmicroemulsionmethodThematerialpresentedahighZrdispersioninaluminaanditwashighlyhomogeneouswith uniform particle size narrow pore size distribution andhighsurfaceareaThismaterialwasusedascobaltsupportandcomparedwithsimilarmaterialpreparedbyZr impregnatedoncommercial alumina The presence of ZrO2-islands on aluminafavoredthedispersionanddegreeofreductionofcobaltwhile

the high Zr dispersion in the Zr-Al2O3 (ME) material hinderedZrO2crystallizationThisproducedamoreamorphousmaterialleading to ahigherdegreeof CoAl2O4 formationand thereforeincreased selectivity tomethaneand short-chainhydrocarbonsC2-C4ThecatalyticactivityandSC5+isfavouredbytheCoZr-Al2O3

(IM)catalystTheseresultsareattributedtothecatalystporosityandhigherCo0availabilityonthesurfaceHowevereven if thecobaltonZr-Al2O3nanoparticles(preparedbywater-in-oilmicroemulsion)isnotthebestcatalystforCOhydrogenationreactionwhen a high C5+ selectivity is desired the material has verygoodpropertiestobeconsideredforotherapplicationssuchasbasedmaterial in three-way-catalyst or as catalyst support forothercatalyticreactionlikehydrodesulphurizationortostabilizealuminaphaseswhenitisusedathightemperatures

Acknowledgments SwedishInternationalDevelopmentCooperationAgency(SIDA)NanoandesnetworkandEuropeanprojectCOSTActionCM1101forfinancialsupportSpecialthankstoDrEmanuelaNegro(DeftUniversityofTechnology)EdgarCardenas(LulearingUniversity)andCesarLeyvaPorras(CIMAVSC)formeasurementsofTEMSEMandHRTEMSTEM

0 200 400 600 800 1000 1200

804CoZr-Al2O3(ME)

CoZr-Al2O3(IM)

722

466

918

742608

350

252

925734

383

318CoAl2O3

Inte

nsity

(au

)

Temperature [degC]400 600 800 1000 1200

968754

428

989749

625

838744

606

CoAl2O3

CoZr-Al2O3 (IM)

CoZr-Al2O3 (ME)

Inte

nsity

(au

)

Temperature [degC]

Figure 5 TPRprofileforthefreshcatalyst(left)andafteractivationat350degCfor16h(right)

GHSV (Ncm3(gh-1) Catalysts XCO () SCH4a

() SC2-C4a () SC5+

a () SCO2 ()

6000 CoAl2O3 65 120 120 750 101500 CoAl2O3 280 85 110 800 056000 CoZr-Al2O3(IM) 120 100 78 810 122350 CoZr-Al2O3(IM) 310 76 60 860 046000 CoZr-Al2O3(ME) 40 200 160 610 301000 CoZr-Al2O3(ME) 270 170 150 670 10

Table 4COconversionlevelsandselectivitydataforthedifferentcatalystsa SelectivitiesareCO2-free

8

ARCHIVOS DE MEDICINAISSN 1698-9465

2017Vol 2 No 2 9

This article is available in httpwwwimedpubcomsynthesis-and-catalysis-open-access

Synthesis and Catalysis Open AccessISSN 2574-0431

References1 Thomas JM (2009) Handbook of Heterogeneous Catalysis In

Angewandte Chemie International Edition Wiley-VCH VerlagWeinheim483390-3391

2 DryME(2002)Thefischerndashtropschprocess1950ndash2000CatalToday71227-241

3 SuaacuterezPRLopezLBarrientosJPardoFBoutonnetMetal(2015)Catalyticconversionofbiomass-derivedsynthesisgastofuels

4 VandeLoosdrechtJBotesFGCiobicaIMFerreiraACGibsonPetal(2013)FischerndashTropschSynthesisCatalystsandChemistryElsevierAmsterdampp525-557

5 GrenobleDCEstadtMMOllisDF(1981)Thechemistryandcatalysisofthewatergasshiftreaction1ThekineticsoversupportedmetalcatalystsJCatal6790-102

6 Tsakoumis NE Roslashnning M Borg Oslash Rytter E Holmen A (2010)Deactivation of cobalt based FischerndashTropsch catalysts A reviewCatalToday154162-182

7 BorgOslashEriSBlekkanEAStorsaeligterSWigumHetal(2007)FischerndashTropschsynthesisoverγ-alumina-supportedcobaltcatalystsEffectofsupportvariablesJCatal24889-100

8 MoradiGRBasirMMTaebAKiennemannA(2003)PromotionofCoSiO2FischerndashTropschcatalystswithzirconiumCatalCommun427-32

9 MiyazawaTHanaokaTShimuraKHirataS(2014)FischerndashTropschsynthesis over aCoSiO2 catalystmodifiedwithMn- andZrunderpracticalconditionsCatalCommun5736-39

10 Miyazawa T Hanaoka T Shimura K Hirata S (2013) Mn and Zrmodified CoSiO2 catalysts development in slurry-phase FischerndashTropschsynthesisAppliedCatalysisAGeneral46747-54

11 LiuYChenJFangKWangYSunY(2007)Alargepore-sizemesoporouszirconiasupportedcobaltcatalystwithgoodperformanceinFischerndashTropschsynthesisCatalCommun8945-949

12 Li ZWu J Yu JHanDWuL et al (2016)Effectof incorporationmanner of Zr on the CoSBA-15 catalyst for the FischerndashTropschsynthesisJMolCatalAChem424384-392

13 ShimuraKMiyazawaTHanaokaTHirataS(2015)FischerndashTropschsynthesisoveraluminasupportedcobaltcatalystEffectofpromoteradditionAppliedCatalysisAGeneral4941-11

14 Enache DI Roy-Auberger M Revel R (2014) Differences in thecharacteristics and catalytic properties of cobalt-based FischerndashTropsch catalysts supported on zirconia and alumina AppliedCatalysisAGeneral26851-60

15 RohrF LindvaringgOAHolmenABlekkanEA (2000)FischerndashTropschsynthesis over cobalt catalysts supported on zirconia-modifiedaluminaCatalToday58247-254

16 Jongsomjit B Panpranot J Goodwin JG (2003) Effect of zirconia-modifiedaluminaonthepropertiesofCoγ-Al2O3catalysts JCatal21566-77

17 Jacobs G Das TK Zhang Y Li J Racoillet G et al (2002) FischerndashTropsch synthesis support loading and promoter effects on thereducibility of cobalt catalysts Applied Catalysis A General 233263-281

18 Boutonnet M Marinas A Montes V Suaacuterez-Paris R Saacutenchez-Domınguez M (2016) Nanocatalysts Synthesis in Nanostructured

Liquid Media and Their Application in Energy and Production ofChemicalsinNanocolloidsElsevierAmsterdampp211-246

19 KombaiahKVijayaJJKennedyLJBououdinaMAl-LohedanHAetal(2017)StudiesonOpuntiadileniihawmediatedmultifunctionalZnFe2O4nanoparticlesOpticalmagneticandcatalyticapplicationsMaterChemPhys194153-164

20 Singh AK (2016) Structure Synthesis and Application ofNanoparticlesinEngineeredNanoparticlesAcademicPressBostonpp19-76

21 Eriksson S Nyleacuten U Rojas S Boutonnet M (2004) Preparationof catalysts from microemulsions and their applications inheterogeneouscatalysisApplCatalA265207-219

22 Pardo-Tarifa F Cabrera S Sanchez-Dominguez M Boutonnet M(2017) Ce-promoted CoAl 2 O 3 catalysts for Fischer-TropschsynthesisIntJHydrogenEnergy429754-9765

23 BoutonnetMSanchez-DominguezM(2017)MicroemulsiondropletstocatalyticallyactivenanoparticlesHowtheapplicationofcolloidaltools in catalysis aims towell design and efficient catalysts CatalToday28589-103

24 MisonoM(2013)ChemistryandCatalysisofMixedOxidesStudSurfSciCatal25-65

25 Sprague MJ (1985) Characterization of heterogeneous catalystsChemieIngenieurTechnik57430-430

26 LemaitreJLDelannayPGF(1984)CharacterizationofHeterogeneousCatalystsDenkerNewYork299-365

27 Schanke D Vada S Blekkan EA Hilmen AM Hoff A et al (1995)StudyofPt-promotedcobaltCOhydrogenationcatalystsJCatal15685-95

28 LoumlgdbergSLualdiMJaumlraringsSWalmsleyJCBlekkanEAetal(2010)Ontheselectivityofcobalt-basedFischerndashTropschcatalystsevidenceforacommonprecursorformethaneandlong-chainhydrocarbonsJCatal27484-98

29 ReuelRCBartholomewCH(1984)ThestoichiometriesofH2andCOadsorptionsoncobaltEffectsofsupportandpreparationJCatal8563-77

30 Jones RD Bartholomew CH (1988) Improved flow technique formeasurementofhydrogen chemisorptiononmetal catalystsApplCatal3977-88

31 Bhatia S Beltramini J Do DD (1990) Temperature programmedanalysisanditsapplicationsincatalyticsystemsCatalToday7309-438

32 Lualdi M Loumlgdberg S Regali F Boutonnet M Jaumlrarings S (2011)Investigation of mixtures of a Co-based catalyst and a Cu-basedcatalyst for the FischerndashTropsch synthesis with bio-syngas theimportanceofindigenouswaterTopCatal54977-985

33 Storsaeligter S Borg Oslash Blekkan EA Holmen A (2005) Study of theeffectofwateronFischerndashTropschsynthesisoversupportedcobaltcatalystsJCatal231405-419

34 Lualdi M (2012) Fischer-Tropsch Synthesis over Cobalt-basedCatalystsforBTLApplications

35 BoutonnetMLoumlgdbergSSvenssonEE(2008)RecentdevelopmentsintheapplicationofnanoparticlespreparedfromwomicroemulsionsinheterogeneouscatalysisCurrOpinColloidInterfaceSci13270-286

36 ChandradassJKimKH(2009)Effectofacidityonthecitrate-nitrate

9

ARCHIVOS DE MEDICINAISSN 1698-9465

2017Vol 2 No 2 9

copy Under License of Creative Commons Attribution 30 License

Synthesis and Catalysis Open AccessISSN 2574-0431

combustion synthesis of alumina-zirconia composite powderMetMaterInt151039-1043

37 Baudiacuten C (2014) Processing of Alumina and CorrespondingCompositesComprehensiveHardMaterials3172

38 ThommesMKanekoKNeimarkAVOlivier JP Rodriguez-ReinosoFetal(2015)Physisorptionofgaseswithspecialreferencetotheevaluation of surface area and pore size distribution Pure ApplChem871051-1069

39 MartiacutenezAPrietoGRollaacutenJ(2009)Nanofibrousγ-Al2O3assupportforCo-basedFischerndashTropschcatalystsponderingtherelevanceofdiffusionalanddispersioneffectsoncatalyticperformance JCatal263292-305

40 Liu C Li J Zhang Y Chen S Zhu J et al (2012) FischerndashTropschsynthesisovercobaltcatalystssupportedonnanostructuredaluminawithvariousmorphologiesJMolCatalAChem363335-342

41 CastnerDGWatsonPRChanIY(1990)X-rayabsorptionspectroscopy

X-rayphotoelectronspectroscopyandanalyticalelectronmicroscopystudiesofcobaltcatalysts2HydrogenreductionpropertiesJPhysChem94819-828

42 OslashyvindBMagnusRSOslashlviSAndersH(2007)Identificationofcobaltspecies during temperature programmed reduction of Fischer-TropschcatalystsStudiesinSurfaceScienceandCatalysis163255-272

43 Topsoslashe NY Topsoslashe H (1982) Adsorption studies onhydrodesulfurization catalysts I Infrared and volumetric study ofNOadsorptiononalumina-supportedCoMoandCo-MocatalystsintheircalcinedstateJCatal75354-374

44 SimionatoMAssafEM(2003)Preparationandcharacterizationofalumina-supportedCoandAgCocatalystsMaterRes6535-539

45 VandeLoosdrechtJVanderHaarMVanderKraanAMVanDillenAJGeusJW(1997)PreparationandpropertiesofsupportedcobaltcatalystsforFischer-TropschsynthesisApplCatalA150365-376

Page 8: Synthesis and Characterization of Novel Zr-Al2O3 ... Prepared2 by Microemulsion Method and Its Use as Cobalt Catalyst Support for the CO Hydrogenation Reaction. Synth Catal. 2017,

8

ARCHIVOS DE MEDICINAISSN 1698-9465

2017Vol 2 No 2 9

This article is available in httpwwwimedpubcomsynthesis-and-catalysis-open-access

Synthesis and Catalysis Open AccessISSN 2574-0431

References1 Thomas JM (2009) Handbook of Heterogeneous Catalysis In

Angewandte Chemie International Edition Wiley-VCH VerlagWeinheim483390-3391

2 DryME(2002)Thefischerndashtropschprocess1950ndash2000CatalToday71227-241

3 SuaacuterezPRLopezLBarrientosJPardoFBoutonnetMetal(2015)Catalyticconversionofbiomass-derivedsynthesisgastofuels

4 VandeLoosdrechtJBotesFGCiobicaIMFerreiraACGibsonPetal(2013)FischerndashTropschSynthesisCatalystsandChemistryElsevierAmsterdampp525-557

5 GrenobleDCEstadtMMOllisDF(1981)Thechemistryandcatalysisofthewatergasshiftreaction1ThekineticsoversupportedmetalcatalystsJCatal6790-102

6 Tsakoumis NE Roslashnning M Borg Oslash Rytter E Holmen A (2010)Deactivation of cobalt based FischerndashTropsch catalysts A reviewCatalToday154162-182

7 BorgOslashEriSBlekkanEAStorsaeligterSWigumHetal(2007)FischerndashTropschsynthesisoverγ-alumina-supportedcobaltcatalystsEffectofsupportvariablesJCatal24889-100

8 MoradiGRBasirMMTaebAKiennemannA(2003)PromotionofCoSiO2FischerndashTropschcatalystswithzirconiumCatalCommun427-32

9 MiyazawaTHanaokaTShimuraKHirataS(2014)FischerndashTropschsynthesis over aCoSiO2 catalystmodifiedwithMn- andZrunderpracticalconditionsCatalCommun5736-39

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ARCHIVOS DE MEDICINAISSN 1698-9465

2017Vol 2 No 2 9

copy Under License of Creative Commons Attribution 30 License

Synthesis and Catalysis Open AccessISSN 2574-0431

combustion synthesis of alumina-zirconia composite powderMetMaterInt151039-1043

37 Baudiacuten C (2014) Processing of Alumina and CorrespondingCompositesComprehensiveHardMaterials3172

38 ThommesMKanekoKNeimarkAVOlivier JP Rodriguez-ReinosoFetal(2015)Physisorptionofgaseswithspecialreferencetotheevaluation of surface area and pore size distribution Pure ApplChem871051-1069

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9

ARCHIVOS DE MEDICINAISSN 1698-9465

2017Vol 2 No 2 9

copy Under License of Creative Commons Attribution 30 License

Synthesis and Catalysis Open AccessISSN 2574-0431

combustion synthesis of alumina-zirconia composite powderMetMaterInt151039-1043

37 Baudiacuten C (2014) Processing of Alumina and CorrespondingCompositesComprehensiveHardMaterials3172

38 ThommesMKanekoKNeimarkAVOlivier JP Rodriguez-ReinosoFetal(2015)Physisorptionofgaseswithspecialreferencetotheevaluation of surface area and pore size distribution Pure ApplChem871051-1069

39 MartiacutenezAPrietoGRollaacutenJ(2009)Nanofibrousγ-Al2O3assupportforCo-basedFischerndashTropschcatalystsponderingtherelevanceofdiffusionalanddispersioneffectsoncatalyticperformance JCatal263292-305

40 Liu C Li J Zhang Y Chen S Zhu J et al (2012) FischerndashTropschsynthesisovercobaltcatalystssupportedonnanostructuredaluminawithvariousmorphologiesJMolCatalAChem363335-342

41 CastnerDGWatsonPRChanIY(1990)X-rayabsorptionspectroscopy

X-rayphotoelectronspectroscopyandanalyticalelectronmicroscopystudiesofcobaltcatalysts2HydrogenreductionpropertiesJPhysChem94819-828

42 OslashyvindBMagnusRSOslashlviSAndersH(2007)Identificationofcobaltspecies during temperature programmed reduction of Fischer-TropschcatalystsStudiesinSurfaceScienceandCatalysis163255-272

43 Topsoslashe NY Topsoslashe H (1982) Adsorption studies onhydrodesulfurization catalysts I Infrared and volumetric study ofNOadsorptiononalumina-supportedCoMoandCo-MocatalystsintheircalcinedstateJCatal75354-374

44 SimionatoMAssafEM(2003)Preparationandcharacterizationofalumina-supportedCoandAgCocatalystsMaterRes6535-539

45 VandeLoosdrechtJVanderHaarMVanderKraanAMVanDillenAJGeusJW(1997)PreparationandpropertiesofsupportedcobaltcatalystsforFischer-TropschsynthesisApplCatalA150365-376


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