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ACS Catal. 2016, 6 (10), pp 6935-6947DOI: 10.1021/acscatal.6b01685
High Performance Au−Pd Supported on 3D Hybrid Strontium- Substituted Lanthanum Manganite Perovskite Catalyst for MethaneCombustionYuan Wang†, Hamidreza Arandiyan*†, Jason Scott*†, Mandana Akia‡, Hongxing Dai*§, Jiguang Deng§, Kondo-Francois Aguey-Zinsou⊥, and Rose Amal†
† Particles and Catalysis Research Group, School of Chemical Engineering, The University of New South Wales, Sydney, New South Wales 2052, Australia⊥MERLin Group, School of Chemical Engineering, The University of New South Wales, Sydney, New South Wales 2052, Australia‡Mechanical Engineering Department, University of Texas-Rio Grande Valley, 1201 West University Drive, Edinburg, Texas 78539, United States§Beijing Key Laboratory for Green Catalysis and Separation, and Laboratory of Catalysis Chemistry and Nanoscience, Beijing University of Technology, Beijing 100124, China
Key ContactScientia Prof. Rose AmalSchool of Chemical EngineeringUniversity of New South WalesTel: +61 2 93854361Email: [email protected]
Low Emission Abundant Source Environmental Friendly
CO2 Emissions from Fossil Energy Sources
Nature Gas Vehicles
• NGVA Europe, https://www.ngva.eu/ • BP statistics, http://www.bp.com/content/dam/bp/pdf/energy-economics/statistical-review-2015/bp-statistical-review-of-world-energy-2015-full-report.pdf• Natural gas, https://www.wintershall.com/crude-oil-natural-gas/natural-gas.html
Introduction
PVANaPdCl4
HAuCl4 3DOM LSMO
(1)
Stir
Step 1: Mixing the HAuCl4, PdCl2, PVA solution and LSMO catalyst and stirring for 20min.
Step 2: Replacing stir system to N2 gas bubble system and adding NaBH4 solution under the ice bath.
Step 3: After bubble treatment for 8h and standing for overnight, the wet solid catalyst was filtered and washed by distilled water and ethanol to remove the Cl- ions.
Step 4: Drying at 100°C in oven for 12h and calcining at ramp 1°C/min to 450ºC and keeping for 3h.
√ Clear water: Bubble treatment for 8h and standing for overnight.
×Yellow water: Bubble treatment for 6h. There are noble metal particles in the water.
(3)Distilled waterEthanol
Vacuum
(4)
Tube furnace
NaBH4
(2)N2
3DOM LSMOAu, Pd NPs
Ice bath
Synthesis Strategy—Au-Pd/3DOM LSMO
Synthesis process of zAuxPdy /3DOM LSMO (z=1, 2 and 3 wt%, molar ratio Au/Pd: x:y=1:2) samples
HRSEM and 3D-eAFM images of PMMA, 3DOM LSMO, noble metal supported 3DOM LSMO and 1DDN LSMO
(b) PMMA hard template
100 nm
(j) 1Au/3DOM LSMO
2 μm
(c) 1AuPd/1DDN LSMO
(g) 1AuPd/3DOM LSMO
400 nm
2 μm
(d) 3DOM LSMO
400 nm
(e) 3DOM LSMO
400 nm
(k) 1Pd/3DOM LSMO
2 μm
(i) 1Au/3DOM LSMO
100 nm
(h) 1AuPd/3DOM LSMO
First la
yerSecond la
yer
Building block
Window holeWall thickness
100 nm
(f) 3DOM LSMO
140n
m
100 nm
(l) 1Pd/3DOM LSMO
132n
m13
8nm
400 nm
(a) PMMA hard template
218n
m
20 nm
(f) 3AuPd/3DOM LSMO
50 nm
(h) 1Pd/3DOM LSMO
50 nm
(a) 1AuPd/3DOM LSMO
50 nm
(d) 2AuPd/3DOM LSMO
50 nm
(k) 1Au/3DOM LSMO
2 nm
(c) 1AuPd/3DOM LSMO
0.213 nm 0.207 nm
0.261 nm
(e) 2AuPd/3DOM LSMO
2 nm
0.216 nm
0.222 nm2 nm
(g) 3AuPd/3DOM LSMO
0.215 nm0.260 nm
2 nm
(j) 1Pd/3DOM LSMO
0.206 nm0.260 nm
2 nm
(l) 1Au/3DOM LSMO
0.223 nm
1 2 3 4 50
10
20
30
Freq
uenc
y (%
)
Nanoparticle Size (nm)10 nm
(i) 1Pd/3DOM LSMO
1 2 3 4 50
5
10
15
20
25
Freq
uenc
y (%
)
Nanoparticle Size (nm)
10 nm
(b) 1AuPd/3DOM LSMO
1 2 3 4 50
10
20
30
40
Freq
uenc
y (%
)
Nanoparticle Size (nm)
0.262 nm
d= 2.15 nm
d= 2.25 nmd= 2.35 nm
(c)
(f)(d)
Pd(e)
Au
(a)
Pd
(b)
Au Pd+Au
HAADF-STEM images and EDS elemental maps for 1AuPd/3DOM LSMO sample of (a-c) EDS elemental maps of Pd, Au and combined of Au+Pd, (d, e) 3D visualization of Pd and Au and (f) EDS intensity line profiles extracted from the spectrum image along the line drawn on image (c)
Pd and Au atoms are well dispersed on the nanoparticle
28 42 56 70 84
(a)
(b)
(c)
(d)
(e)
In
tens
ity (a
.u.)
2 Theta (Deg.)
(f)
LSMO perovskite No. 04-016-6114
Macropore diameter, BET surface areas, crystallite sizes (Dsupport), pore volume, noble metal particle size and real AuPd content of samples.
a Determined by the ICP-AES results; b Calculated based on the XPS results;
SampleAu contenta
(wt%)
Pd contenta
(wt%)
Noble metal contenta
BET surface area
(m2/g)
Surface element compositionb
Nominal
(wt%)
Measured
(wt%)
Mn4+/Mn3+ molar
ratio
Oads/Olatt
molar ratio
Auδ+/Au0 molar
ratio
Pd2+/Pd0
molar ratio
3DOM LSMO - - - - 32.4 1.42 1.04 - -
1Au/3DOM LSMO 0.94 - 1 0.94 32.6 1.21 1.16 0.20 -
1Pd/3DOM LSMO - 0.85 1 0.85 32.0 0.91 1.38 - 0.71
1AuPd/3DOM LSMO 0.44 0.48 1 0.92 33.6 1.15 1.21 0.31 0.73
2AuPd/3DOM LSMO 0.95 0.98 2 1.93 33.3 1.03 1.37 0.39 0.85
3AuPd/3DOM LSMO 1.42 1.50 3 2.92 33.8 0.89 1.49 0.42 1.23
1AuPd/1DDN LSMO 0.45 0.50 1 0.95 4.32 1.26 1.09 0.28 0.50
92 90 88 86 84 82 80
1Au/3DOM LSMO 1AuPd/3DOM LSMO 2AuPd/3DOM LSMO 3AuPd/3DOM LSMO
Binding energy (eV)In
tens
ity (a
.u.)
Au 4f
344 342 340 338 336 334 332
Binding energy (eV)
Inte
nsity
(a.u
.)
Pd 3d 1Pd/3DOM LSMO
1AuPd/3DOM LSMO 2AuPd/3DOM LSMO 3AuPd/3DOM LSMO
(1) (2)
XRD and XPS
• XRD profile of (a) 3DOM LSMO, (b) 1Au/3DOM LSMO, (c) 1Pd/3DOM LSMO, (d) 1AuPd/3DOM LSMO, (e) 2AuPd/3DOM LSMO, (f) 3AuPd/3DOM LSMO.• Au 4f and Pd 3d XPS spectra of the monometallic and bimetallic Au-Pd supported catalysts.
Shifted 0.3 eV Shifted 0.5 eV
480 600 720 8400.00
0.01
0.02
0.03
0.04
0.05
680
860
665
1DDN LSMO 3DOM LSMO
Inte
nsity
(a.u
.)
Temperature (°C)
Brønsted acid sites
Weak acid sites
110 220 330 440 550 660 770
Inte
nsity
(a.u
.)
Temperature (°C)
peakpeak250 620
125542
162608
643200
160
660
305 640
380310 650
(g)
(a)
(b)
(c)
(d)
(e)
(f)
• H2-TPR profiles of (a) 3DOM LSMO, (b) 1Au/3DOM LSMO, (c) 1Pd/3DOM LSMO, (d) 1AuPd/3DOM LSMO, (e) 2AuPd/3DOM LSMO, (f) 3AuPd/3DOM LSMO and (g) 1AuPd/1DDN LSMO.
• NH3-TPD profiles of 1DDN LSMO and 3DOM LSMO samples.
H2-TPR and NH3-TPD
La3+ and Sr2+ are non-reducible under the H2-TPR conditions
2
III IV III1 1 3 2 1 23
1 1La Sr Mn Mn O H La Sr Mn O H O2 2
xx x x x x xx x
21 2 2 3 231 1 1La Sr MnO H (1 )La O MnO SrO H O2 2 2
xx x x x
α-peak:
β-peak:
Rich Brønsted acid sites and weak acid sites (Lewis acid sites) on the surface of 3DOM structure
The rich Brønsted acid sites were reported to have remarkable synergistic effect with the supported Pd and Pt NPs, helping to adsorb and activate reactant molecules during the catalytic process, Scientific Reports, 3 (2013), 2349.
Methane conversion versus reaction temperature of (a) 1Au/3DOM LSMO, (b) 1Pd/3DOM LSMO, (c) physical mixture of 1Pd/3DOM LSMO and 1Au/3DOM LSMO, (d) 1AuPd/3DOM LSMO and (B) Dependence of methane conversion at 350 °C and ratio of Oads/Olatt, Pd2+/Pd0 and Auδ+/Au0.
Catalytic Activity
Sample
Methane conversion (°C)
T10% T50% T90%
3DOM LSMO 344 384 508
1Au/3DOM LSMO 338 375 402
1Pd/3DOM LSMO 323 358 378
1Au+1Pd/3DOM LSMO 340 360 405
1AuPd/3DOM LSMO 304 350 382
2AuPd/3DOM LSMO 280 331 354
3AuPd/3DOM LSMO 265 314 336
1AuPd/1DDN LSMO 322 370 400
200 300 400 500 6000
50
1000
50
1000
50
1000
50
100
(d)
(c)
(a)
(b)
Met
hane
conv
ersio
n (%
)
Temperature (°C)
(A)Au atomPd atom
+¿
Au atomPd atom
Pd atom
Au atom
3DOM LSMO3DOM LSMO
3DOM LSMO
3DOM LSMO
3DOM LSMO
T50%=350°C
Methane Combustion
Table. Catalytic activites of the 3DOM, AuPd/3DOM LSMO, AuPd/1DDN LSMO samples.
Mixture
FurnaceGC
Micro-TCD
Mass Flow Controller
15.6 16.8 18.0
0.0
0.2
0.4
0.6
0.8
TOF
cat (
×10-3
s-1)
H2 consumption (mmol/gcat)
1AuPd/3DOM LSMO
1Pd/3DOM LSMO
3AuPd/3DOM LSMO
2AuPd/3DOM LSMO
1AuPd/3DOM LSMO
3DOM LSMO
3DOM LSMO
Au atomPd atom
3DOM LSMO
Pd atom
3DOM LSMO
Au atom
Good catalytic performance for bimetallic Au-Pd/3DOM LSMO is due to the combination of many aspects:1. Good low-temperature reducibility;2. High surface areas and internal surface;3. Rich Brønsted acid sites; 4. High concentration of surface adsorbed oxygen species;5. More active phase (Pd2+ and Auδ+) with synergistic effect;
• Dependence of methane conversion at 350 °C and ratio of Oads/Olatt, Pd2+/Pd0 and Auδ+/Au0 • Correlation of the TOF at 270 °C and the H2 consumption over the obtained samples
0
20
40
60
80
100
0.0
0.2
0.4
0.6
0.8
1.0
1.2
1.4
M
etha
ne c
onve
rsio
n (%
)
Rat
io o
f sur
face
spe
cies
Activity at 350°C
Pd2+/Pd0
Au&+/Au0
Oads
/Olatt
Catalytic Performance Evaluation
This work can be found in the ACS Catal. 2016, 6 (10), pp 6935-6947
DOI: 10.1021/acscatal.6b01685
More information on the Particle Catalysis Research Group at:
http://www.pcrg.unsw.edu.au/
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