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Ni-phyllosilicate structure derived Ni-SiO 2 -MgO catalysts for bi- reforming applications: acidity, basicity and thermal stability. J. Ashok, Z. Bian, Z. Wang and S.Kawi* Experimental The surface area and total pore volume of the freshly calcined, reduced and spent catalysts were measured by N 2 physical adsorption at −196 °C in an ASAP 2020 instrument. Prior to N 2 physical adsorption, all the catalysts were degassed under vacuum at 300°C for 3 h. The specific surface area was calculated by applying the Brunauer-Emmett-Teller (BET) method. HRTEM system JEOL JEM-2100F was used to analyze surface morphology of calcined, reduced and spent catalysts. The catalyst sample was ultrasonically dispersed in ethanol and spread over perforated copper grids. The X-ray diffraction (XRD) patterns of fresh, reduced and spent catalysts were measured on a Shimadzu XRD-6000 diffractometer using Cu Kα radiation. The catalyst was scanned for 2θ range between 10° to 60° at a ramp rate of 2°/min. Ni and Mg compositions of the catalysts were measured with Thermal Scientific iCAP 6000 ICP-OES Analyser. 15mg powder was dissolved in a mixture of 0.5 ml HF (48%), 2mL HNO 3 (65%) and 40mL DI water aided by ultrasonic treatment. Ni and Mg ICP standard solution diluted to appropriate concentrations was used to prepare the calibration curve. Electronic Supplementary Material (ESI) for Catalysis Science & Technology. This journal is © The Royal Society of Chemistry 2018

7KLV reforming applications: acidity, basicity and …J. Ashok, Z. Bian, Z. Wang and S.Kawi* Experimental The surface area and total pore volume of the freshly calcined, reduced and

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Page 1: 7KLV reforming applications: acidity, basicity and …J. Ashok, Z. Bian, Z. Wang and S.Kawi* Experimental The surface area and total pore volume of the freshly calcined, reduced and

Ni-phyllosilicate structure derived Ni-SiO2-MgO catalysts for bi-

reforming applications: acidity, basicity and thermal stability.

J. Ashok, Z. Bian, Z. Wang and S.Kawi*

Experimental

The surface area and total pore volume of the freshly calcined, reduced and spent catalysts were

measured by N2 physical adsorption at −196 °C in an ASAP 2020 instrument. Prior to N2

physical adsorption, all the catalysts were degassed under vacuum at 300°C for 3 h. The specific

surface area was calculated by applying the Brunauer-Emmett-Teller (BET) method. HRTEM

system JEOL JEM-2100F was used to analyze surface morphology of calcined, reduced and

spent catalysts. The catalyst sample was ultrasonically dispersed in ethanol and spread over

perforated copper grids. The X-ray diffraction (XRD) patterns of fresh, reduced and spent

catalysts were measured on a Shimadzu XRD-6000 diffractometer using Cu Kα radiation. The

catalyst was scanned for 2θ range between 10° to 60° at a ramp rate of 2°/min.

Ni and Mg compositions of the catalysts were measured with Thermal Scientific iCAP 6000

ICP-OES Analyser. 15mg powder was dissolved in a mixture of 0.5 ml HF (48%), 2mL HNO3

(65%) and 40mL DI water aided by ultrasonic treatment. Ni and Mg ICP standard solution

diluted to appropriate concentrations was used to prepare the calibration curve.

Electronic Supplementary Material (ESI) for Catalysis Science & Technology.This journal is © The Royal Society of Chemistry 2018

Page 2: 7KLV reforming applications: acidity, basicity and …J. Ashok, Z. Bian, Z. Wang and S.Kawi* Experimental The surface area and total pore volume of the freshly calcined, reduced and

The H2 Temperature-programmed reduction (TPR) and CO2-Temperature-programmed

reduction (TPD) experiments was conducted using Thermo Scientific TPDRO 1100 series

system (with TCD detector). For H2-TPR, 0.03 g of catalyst sample was outgassed in N2 gas for

1 h at 300°C to remove any moisture and then cooled to room temperature. Then, 5% H2/N2 gas

was introduced to the catalyst while the temperature of the furnace was increased to 950°C (ramp

rate of 10°C/min). For CO2-TPD, about 100 mg of catalyst sample was reduced at 750°C for 1 h

under H2 gas (30 mL/min). After that, the samples were cooled to 50°C where CO2 adsorption

was carried out for 30 min. Then the samples were purged in He gas for 30 min. Desorption of

CO2 took place while heating the sample from 50 to 1000°C (ramp rate of 10°C/min).

The surface Ni metal content and dispersion was calculated by using N2O titration

method. Prior to N2O titration at 70 °C, the sample (W = 30 mg) was reduced at 750 °C

for 1 h under H2 gas, and then cooled to 70 °C in helium gas flow of 30 mL/min. At this

temperature, the N2O decomposition was carried out by introducing several pulses of N2O

gas using 99.99% N2O with a loop volume of 344 µL. This was followed by TPR with

temperatures up to 750 °C performed in the TPDRO 1100 series system. The amount of

the oxidized Ni surface atoms by N2O decomposition was estimated by measuring the H2

consumed during TPR analysis, in accordance to Eq’s below.

Ni0 + N2O → NiO + N2

NiO + H2 → Ni0 + H2O

The reduced and spent catalysts surface analysis was performed using X-ray

photoelectron spectroscopy (XPS) from a KRATOS AXIS Hsi 165 equipped with Mg-Kα source

(1253.6 eV). Prior to the analysis for reduced catalysts, the catalyst was reduced at 750ºC under

Page 3: 7KLV reforming applications: acidity, basicity and …J. Ashok, Z. Bian, Z. Wang and S.Kawi* Experimental The surface area and total pore volume of the freshly calcined, reduced and

H2 for 1 h. For spent catalyst, the catalysts were used as collected from reforming reactor. Then

the sample was mounted on the standard sample stub using double-sided adhesive tapes. All

binding energies were referenced to C 1s hydrocarbon peak at 284.6 eV. Shimadzu DTG-60

thermo gravimetric analyzer was used to analyse total amount and nature of deposited carbon on

the spent catalysts. Around 10 mg of spent catalyst was used in each DTA/TGA experiment and

heated in air to 1000°C with a heating rate of 10°C/min.

Table S1. The amount of metal precursors taken for synthesizing Ni-SiO2-Mg[x]

catalysts, nominal and actual metal contents present in the calcined catalysts

Amount of metal precursor[a]Catalyst

Ni nitrate

(grams)

SiO2

(grams)

Mg nitrate

(grams)

Nominal wt%

composition

(Ni:SiO2:Mg)

Actual wt%

composition

(Ni:SiO2:MgO)

Ni-SiO2 1.49 3.4 -- 15:85:0 13.1±0.5:--:--

Ni-SiO2-MgO[25] 1.49 2.4 5.27 15:60:25 13.8±0.6:--:22.2±1

Ni-SiO2-MgO[40] 1.49 1.8 8.44 15:45:40 11.50.4:--:35.60.6

Ni-SiO2-MgO[55] 1.49 1.2 11.60 15:30:55 12.20.6:--:52.60.8

Ni-MgO[85] 1.49 -- 17.93 15:00:85 9.40.5:--: 611

[a] calculated to prepare 2g of the calcined catalyst; [b] determined using ICP-OES analyzer.

Page 4: 7KLV reforming applications: acidity, basicity and …J. Ashok, Z. Bian, Z. Wang and S.Kawi* Experimental The surface area and total pore volume of the freshly calcined, reduced and

0.0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1.0

(e)(d)

(c)

(b)

Qua

ntity

ads

orbe

d/de

sorb

ed(c

m3 /g

)

Relative pressure/(P/Po)

100

(a)

Figure S1. N2 adsorption-desorption isotherms of calcined (a) Ni-MgO, (b) Ni-SiO2-MgO[55],

(c) Ni-SiO2-MgO[40], (d) Ni-SiO2-MgO[25] and (e) Ni-SiO2 samples.

Page 5: 7KLV reforming applications: acidity, basicity and …J. Ashok, Z. Bian, Z. Wang and S.Kawi* Experimental The surface area and total pore volume of the freshly calcined, reduced and

0 3 6 9 12 15 180

20

40

60

80M

etha

ne c

onve

rsio

n/(%

)

Time on stream/(h)

Ni-SiO2

Ni-SiO2-MgO[25] Ni-SiO2-MgO[40] Ni-SiO2-MgO[55] Ni-MgO

(A)

0 2 4 6 8 10 12 14 16 18 200

20

40

60

80

(B)

CO2 c

onve

rsio

n/(%

)

Time on stream/(h)

Ni-SiO2

Ni-SiO2-MgO[25] Ni-SiO2-MgO[40] Ni-SiO2-MgO[55] Ni-MgO

Figure S2. Time dependant (A) CH4 conversion and (B) CO2 conversion over Ni-SiO2-MgO[x]

catalysts during bi-reforming of methane reaction. Conditions: W = 0.01 g; CH4 = 20 mL/min;

CO2 = 10 mL/min; Steam = 20 mL/min; He = 50 mL/min; Reduction temperature = 750°C/1 h;

and Reaction temperature = 750°C.

Page 6: 7KLV reforming applications: acidity, basicity and …J. Ashok, Z. Bian, Z. Wang and S.Kawi* Experimental The surface area and total pore volume of the freshly calcined, reduced and

500 550 600 650 700 750 800 850 900-25

0

25

50

75

100

CH4 conversion H2O conversion CO2 conversion CH4

H2O CO2

CO H2

Temperature/0C

CH4/C

O2/H

2O c

onve

rsio

n(%

)

solid

open

0

10

20

30

40

50

60 Products distribution/(molar flow rate)

Figure S3. Calculated thermodynamic equilibrium conversion for bi-reforming of

methane reaction. Condition: CH4 = 20mL/min, H2O = 20 mL/min, CO2 = 10mL/min and He =

50mL/min.

500 550 600 650 700 750 800 850 900-25

0

25

50

75

100

CH4/C

O2 c

onve

rsio

n/(%

)

Temperature/0C

CH4 (equilibrium) CO2 (equilibrium) CH4 (experimental) CO2 (experimental)

Figure S4. Actual and calculated thermodynamic equilibrium CH4 and CO2 conversions

during bi-reforming of methane reaction. Condition: CH4 = 20mL/min, CO2 = 10mL/min, H2O =

20mL/min and He = 50mL/min.

Page 7: 7KLV reforming applications: acidity, basicity and …J. Ashok, Z. Bian, Z. Wang and S.Kawi* Experimental The surface area and total pore volume of the freshly calcined, reduced and

0 5 10 15 20 25 30 35 40 45 500

20

40

60

80

100 CH4 (7500C); CH4 (7000C); CH4 (6500C) CO2 (7500C; CO2 (7000C); CO2 (6500C) H2/CO (7500C); H2/CO (7000C); H2/CO (6500C)

Time on stream/(h)

CH4/C

O2 c

onve

rsio

n/(%

)

0.8

1.2

1.6

2.0

2.4H

2 /CO

Figure S5. Bi-reforming of methane over Ni-SiO2-MgO[55] at various reaction temperatures

Figure S5 depicts the Bi-reforming of methane (BRM) performance over Ni-SiO2-MgO[55] at

reaction temperature between 650 and 750°C. The result shows that both CH4 and CO2

conversions are decreased with decrease in reaction temperature. The H2/CO values at 650°C is

slightly higher than other reaction temperatures, which is possibly due to better water-gas-shift

reaction at lower reaction temperature.

Page 8: 7KLV reforming applications: acidity, basicity and …J. Ashok, Z. Bian, Z. Wang and S.Kawi* Experimental The surface area and total pore volume of the freshly calcined, reduced and

0 5 10 15 20 25 30 35 40 45 500

20

40

60

80

100

CO2

Time on stream/(h)

CH4/C

O2 c

onve

rsio

n/(%

)(a)

CH4

Condition: CH4:CO2:H2O = 2:1:2

0.0

0.4

0.8

1.2

1.6

2.0

2.4

2.8

H2 /CO

0 5 10 15 20 25 30 35 40 45 500

20

40

60

80

100

Time on steam/(h)

CH4/C

O2 c

onve

rsio

n/(%

)

0.0

0.4

0.8

1.2

1.6

2.0

2.4

2.8

Condition: CH4:CO2:H2O = 2:1:1.5

H2 /CO

CH4

CO2

(b)

Page 9: 7KLV reforming applications: acidity, basicity and …J. Ashok, Z. Bian, Z. Wang and S.Kawi* Experimental The surface area and total pore volume of the freshly calcined, reduced and

0 5 10 15 20 25 30 35 40 45 500

20

40

60

80

100

Condition: CH4:CO2:H2O = 2:1:1

Time on stream/(%)

CH4/C

O2 c

onve

rsio

n/(%

)

CO2

CH4

(c)

0.0

0.4

0.8

1.2

1.6

2.0

2.4

2.8

H2 /CO

Figure S6. Bi-reforming of methane over Ni-SiO2-MgO[55] catalyst at various CH4/H2O ratios.

According to Figure S6 the methane conversions were slightly decreased and CO2 conversion

was increased with decreasing steam amount in the feed is observed. This result shows that the

H2/CO values can easily be tuned by changing the amount of steam in the feed.

Page 10: 7KLV reforming applications: acidity, basicity and …J. Ashok, Z. Bian, Z. Wang and S.Kawi* Experimental The surface area and total pore volume of the freshly calcined, reduced and

100 200 300 400 500 600 700 800 900-150

-100

-50

0

50

100

150

750oC 700oC 650oC CH4:H2O = 2:1.5 CH4:H2O = 2:1

Temperature/oC

DTA,

rate

of w

t. lo

ss (d

m/d

T)

50

60

70

80

90

100

110

TGA, weight loss (%

)

Figure S7. DT/TGA profiles for spent Ni-SiO2-MgO[55] catalyst at various reaction conditions.

The carbon formation during reforming reaction is observed at reaction temperature of 650°C

and at low steam condition. The carbon formation is negligible for almost all other reaction

conditions.

1400 1450 1500 1550 1600 1650 1700

0.0

0.1

0.2

0.3

0.4

0.5

LAS

Inte

nsity

/a.u

.

wavenumber/cm-1

150 200 250 300 350 400

LAS

(A) - Ni/SiO2

Page 11: 7KLV reforming applications: acidity, basicity and …J. Ashok, Z. Bian, Z. Wang and S.Kawi* Experimental The surface area and total pore volume of the freshly calcined, reduced and

1400 1450 1500 1550 1600 1650 1700

0.0

0.1

0.2

0.3

0.4

0.5

LAS/BAS BAS

LAS

Inte

nsity

/a.u

.

wavenumber/cm-1

150 200 250 300 350 400

(B) - Ni-SiO2-MgO[25]

LAS

1400 1450 1500 1550 1600 1650 17000.0

0.1

0.2

0.3

0.4

0.5

LAS

BAS

LAS/BAS

Inte

nsity

/a.u

.

wavenumber/cm-1

150 200 250 300 350 400

LAS

(C) - Ni-SiO2-MgO[40]

Page 12: 7KLV reforming applications: acidity, basicity and …J. Ashok, Z. Bian, Z. Wang and S.Kawi* Experimental The surface area and total pore volume of the freshly calcined, reduced and

1400 1450 1500 1550 1600 1650 17000.0

0.2

0.4

0.6

0.8

BASLAS

LAS/BAS

Inte

nsity

/a.u

.

wavenumber/cm-1

150 200 250 300 350 400

LAS

(D) - Ni-SiO2-MgO[55]

1400 1450 1500 1550 1600 1650 17000.0

0.1

0.2

0.3

0.4

0.5

0.6

BASLAS

LAS/BASInte

nsity

/a.u

.

wavenumber/cm-1

150 200 250 300 350 400

LAS

(E) - Ni-MgO

Figure S8. Pyridine-DRIFTS over reduced Ni-SiO2-MgO[x] catalysts. The pyridine is adsorbed

at 150C and desorbed between 150 and 400C in the presence of He gas.

Page 13: 7KLV reforming applications: acidity, basicity and …J. Ashok, Z. Bian, Z. Wang and S.Kawi* Experimental The surface area and total pore volume of the freshly calcined, reduced and

3500 3550 3600 3650 3700 3750 3800-0.1

0.0

0.1

0.2

0.3

0.4

0.5In

tens

ity/a

.u.

wavenumber/cm-1

150 200 250 300 350 400

(A) - Ni-SiO2

(I)-OH(B)-OH

3500 3550 3600 3650 3700 3750 3800-0.1

0.0

0.1

0.2

0.3

0.4

0.5

Inte

nsity

/a.u

.

wavenumber/cm-1

150 200 250 300 350 400

(I)-OH(B)-OH

(T)-OH(B) - Ni-SiO2-MgO[25]

Page 14: 7KLV reforming applications: acidity, basicity and …J. Ashok, Z. Bian, Z. Wang and S.Kawi* Experimental The surface area and total pore volume of the freshly calcined, reduced and

3500 3550 3600 3650 3700 3750 3800

-0.1

0.0

0.1

0.2

0.3

0.4

0.5

(B)-OH

(I)-OH

Inte

nsity

/a.u

.

wavenumber/cm-1

150 200 250 300 350 400

(T)-OH

(C) - Ni-SiO2-MgO[40]

3500 3550 3600 3650 3700 3750 3800

0.0

0.3

0.6

Inte

nsity

/a.u

.

wavenumber/cm-1

150 200 250 300 350 400

(D) - Ni-SiO2-MgO[55]

Page 15: 7KLV reforming applications: acidity, basicity and …J. Ashok, Z. Bian, Z. Wang and S.Kawi* Experimental The surface area and total pore volume of the freshly calcined, reduced and

3500 3550 3600 3650 3700 3750 3800

-0.1

0.0

0.1

0.2

0.3

0.4

0.5

0.6

0.7In

tens

ity/a

.u.

wavenumber/cm-1

150 200 250 300 350 400

(E) - Ni-MgO

Figure S9. Hydroxyls region of Pyridine-DRIFTS over reduced Ni-SiO2-MgO[x] catalysts. The

pyridine is adsorbed at 150C and desorbed between 150 and 400C in the presence of He gas.

0.0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1.0

Qua

ntity

ads

orbe

d/de

sorb

ed(c

m3 /g

)

Relative pressure/(P/Po)

100

(a)

(b)

(c)

(d)

(e)

(A)

Page 16: 7KLV reforming applications: acidity, basicity and …J. Ashok, Z. Bian, Z. Wang and S.Kawi* Experimental The surface area and total pore volume of the freshly calcined, reduced and

0.0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1.0

(e)

(d)

(c)

(b)

Qua

ntity

ads

orbe

d/de

sorb

ed(c

m3 /g

)

Relative pressure/(P/Po)

100

(a)

(B)

Figure S10. N2 adsorption-desorption isotherms of (A) reduced and (B) spent (a) Ni-MgO, (b)

Ni-SiO2-MgO[55], (c) Ni-SiO2-MgO[40], (d) Ni-SiO2-MgO[25] and (e) Ni-SiO2 samples.