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: r.amal@unsw.edu.au

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• 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

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