Ultrafast analysis of catalyst surface

K Asakura

Catalysis Research Center, Hokkaido University, Kita-ku N21W10, Sapporo, Hokkaido 001-0021, Japan

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Polymers and plastics are generate using Catalysts (Ziegler Natter or Kaminsky catalysts)

Automobile catalysts (Pt-Pd-Rh/Al2O3, Pt/CeO2) Photocatalysts(TiO2) Enzyme Fuel cell electrode

What are catalysts?

Automobile catalyst To remove NOx From exhausted gas

They accelerate chemical reaction without changing themselves and important in many fields.

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Three important factors in catalysis

Activity rate determining step Slowest process.

Selectivity ex. Propane oxidation

• No selectivity CO2• High selectivity CH2CHCHO

Life time

3

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Classification of Catalysts

Solid State Catalysts-Heterogeneous catalysts Pt-Rh-Pd/Al2O3 Solid surface plays an important role

Catalyst in Solution Homogeneous catalysts Cross coupling catalysts, Enzyme Chiral synthesis, Metatheses Metal active site is important

Special Active Site Plays an important role.

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Miyaura-Suzuki Reaction

Oxidative addiition

transmetalation

Reductive elimination

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Classification of Catalysts

Solid State Catalysts-Heterogeneous catalysts Pt-Rh-Pd/Al2O3 Solid surface plays an important role

Catalyst in Solution Homogeneous catalysts Cross coupling catalysts, Enzyme Chiral synthesis, Metatheses Metal active site is important

Special Active Site Plays an important role.

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Heterogenous Catalysts

Langmuir Hinshellwood mechanism Horiuchi-Polanyi Mechamism

H2

CH2=CH2 H H CH2-CH3 H

CH3-CH3CH2=CH2

Catalysts

Adsorption Diffusion Reaction

Desorption

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From Unused Biomass to Fuel(A.Fukuoka Angewandte Chem. 2007)

Wood Celulose Solvitol

Alcohols

Gasoline

Plastics

CO2PlantsPhotosynthesis

Pt Catalyst

Fine Chemicals

glucose

Hemicelulose

5C sugarEnzyme

New Chemical industry based on biomassPF-ERL

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Environment Improvement Catalysts

）

mol ）

50

40

30

20

10

0100806040200

3DOM-WO3

WO3

二 m

ol ）

50

40

30

20

10

0100806040200

3DOM-WO3

WO3NP-

Time / min

CO2

mol ）

50

40

30

20

10

0100806040200

3DOM-WO3

WO3

）

50

40

30

20

10

0100806040200

3DOM-WO3

WO3NP-

Light

Photodegradation of VOC Ueda Ohtani et al. J.Material Chem. (2010)

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Soot combution on nanofibered LaMnO3Nanofibered

conventional

Li, S.; Kato, R.; Wang, Q.; Yamanaka, T.; Takeguchi, T.; W., U. Applied Catalysis B: Environmental 2010, 93, 383.

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Rh dimer catalysts （Active for ethylene hydroformylationreaction）K. Asakura, K.K. Bando, Y. Iwasawa, H. Arakawa, K. Isobe, J.Am.Chem.Soc 112 (1990) 9096.

C2H4+CO+H2 C2H5CHO

4 6 8 10 12 14 16-0.20-0.15-0.10-0.050.000.050.100.15

k (

k)

K / 10nm-1

Rh Rh

CC

OO

RCｐ*

OO

SiO2

Rh Rh

C OR

Cｐ*

OO

SiO2

4 6 8 10 12 14 16

-0.15

-0.10

-0.05

0.00

0.05

0.10

0.15

k (

k)

k /10 nm-1

H2ＲC2H5CHO

+CO,+Ｒ

0.270 nmｍ

IR吸収バンド1710 cm-1

IRabsorption band 2032,1969 cm-1

EXAFS before the reaction EXAFS after the adsorption

CO2

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.In-situ studies

Active site is dynamically changed during the reaction

In-situ studies are necessary to determine the reaction mechanisms.

High temperature and high pressure.

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Introduction

Sulfur compounds in fossil fuel. 1.Sulfur is oxidized to sulfurous or sulfuric

acids and is an origin for acid rain.2.It poisons the deNOX catalysts equipped in

cars. 3. Demand for use of low quality oil with high

sulfur contents.

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1990-1994 1995-2000 Post 2000

USA 500 ppm 500 ppm 15 ppm by 2006

Europe 500 ppm 500 ppm 50ppm by 200510 ppm by 2008

Japan 0.2 wt% 500 ppm 50 ppm by 200510 ppm by 200７

Sulfur in fuel is legally restricted more and more strictly.

http://www.epa.gov/apti/course422/ap7b1.html

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s

s

H2+ H2S

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Metal phosphides

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0

20

40

60

80

100

Con

vers

ion

/ %

S

N

HDSHDN

Fe2P/SiO2 MoP Ni2P/SiO2CoP/SiO2 WP Ni-Mo-S/Al2O3

More active than commercially avaialbe NiMoS

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In situ EXAFS .

High pressure cellJ.Phys. Chem.93,4213(1989)

Z.Phys.Chem.,144,105(1985).

Thermocouple

HeaterWater

GasGas

Gas

Window(Acrylic resin)

O-ringQuartz Tube

SampleWater

Water

Water

X-ray

Io I

J.Synchro.Rad.8, 581(2001).J.Chem.Phys. 70 (1979) 4849.

X-ray absorption, Principles, applications, techniques of EXAFS, SEXAFS, and XANES, New York, John Wiley & Sons, 1988.

X-ray windows are set far away from sample.

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Experimental SetupPF-ERL 2011/04/27

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X-rayInfraredThermocouple

Gas injection bulb

Heater

IR and X-ray hit the sampleSample : Ni2P/MCM-4135 mg,15 mm in diameter

Heating803 K by heaterGas introduction

Sample

反応 : C4H4S + 2H2 → C4H8SC4H8S + H2 → H2S + C4H8

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Experimental SetupMCT

InterferometerOptical faiber

IR

X-ray

QMS

Gas controller

ActivitiyQMS

Gas flow

StructureQXAFS

AdsorptionFT-IR

Reaction Cell

KEK, PF BL-9C

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EXAFS of Ni2P under reaction conditions.

2 4 6 8 10 12-0.1

0.0

0.1

0.2

b)

a)

(k)

k / A-1

Before reaction

10 h 4 6 8 10-0.004

-0.002

0.000

0.002

0.004

(k)

k / 10 nm-1

• Ni2P Ni K-edge XAFSDifference Spectrum

•Ni-S at 0.227 nm• with N=0.1.

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Difference spectra in HDS – before reaction

NiP

NiP

P

PNi

S PNi

P

NiP

P

PNi

P

• CF results of Ni-SR=0.227 nm； CN=0.1.

• Judging from the ratio of surface Ni to the bulk ~0.5 S/Ni=0.2±0.2

• Little reaction temperature dependence

k(k

) / 1

0nm

-1

0.00

0.02

0.04

0.06

0.08

0.10

0.12

k / 10 nm-13 104 5 6 7 8 9

Ni – S (FEFF)CN = 0.1, R = 0.227 nm, 2 = 0.0064 Å2

HDS at 513 K

HDS at 553 K

HDS at 593 K

Simulated XAFS based on Ni-S bond

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How does Ni-S bond change?

250 300 350 400 450 500 550 600

0.0

0.1

NN

i-S

T / K0 10 20 30 40 50 600.0

0.1

0.2

t / min

0.0

0.1

0.2

N

i-S

0.0

0.1

0.2

513 K

553 K

593 K

T / K 513 553 593

v/min-1 0.47(3) 0.8(3) 2.5(3)

•Ni-S is rapidly formed and saturated. •Saturation number is 0.1 •Ea=53 kJ/mol for formation reaction of Ni-S

0.1

Time and temperature dependence of Ni-S formation

Formation rate

Saturation number of Ni-S bond

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He HDS反応H2還元

He H2還元240 ℃

530 ℃H2S処理

H2還元

530 ℃

XANES, IR and MS changes during 513 K2B06

2010年9月16日20HDS反応開始

IR

Ni=SXAFS

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Reaction mechanisms

NiPS Formation processes

Ⅰ : Ni-Sformation

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Reaction mechanisms

Hydorgenation processes C-S bond cleavage

C-S bond cleavage

H2S

2H2

NiPS Formation processes

Ⅱ : Ni-SReaction

THT

H2S

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Reaction mechanisms

Hydorgenation processes C-S bond cleavage

C-S bond cleavage

H2S

2H2

Ⅲ : Steadystate

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Time resolved studies=>DXAFSPF-ERL

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• Stedy state- Mixture

• Reaction starts at once- Pump-probe- T-jump, P-Jump- Isotope change

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H.F.J.van’t Bilk, J.B.A.D.van Zon, T.Huizinga, J.C.Vis, D.C.Koningsberger, and R.Prins,J.Am.Chem.Soc., 107 (1985) 3139.

C

ORh

Rhx cluster

CO

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Disruption of Rh clusters on Al2O3 surface by CO at RT

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-4

-2

0

2

4

6420

The k3-weighted EXAFS Fourier transformed functions for Rh/Al2O3 under CO (26.7 kPa) at 298 K measured by DXAFS

together with the curve fittings of the observed FT data and their imaginary parts

-4

-2

0

2

4

6420

-4

-2

0

2

4

6420

0 s 0.6 s 3 s

-4

-2

0

2

4

6420R / 0.1 nm R / 0.1 nm R / 0.1 nm R / 0.1 nm

|FT|[

k3(

k)]

|FT|[

k3(

k)]

|FT|[

k3(

k)]

|FT|[

k3(

k)]

7 s

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(1) Suzuki, A.; Inada, Y.; M.; Nomura, M.; Iwasawa, Y.et al., Angewandte Chemie Inter.Ed. 2003, 42, 4795.

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The values of coordination number

(CN) and bond distance (R)

determined by the curve fitting as a function of CO exposure time

3.0

2.8

2.6

2.4

2.2

2.0

1.886420

Time / s

8

6

4

2

0

CN

R /

0.1

nmRh-Rh

Rh-Rh

Rh-O

Rh-O

Rh-C-(O)

Rh-(C)-O

Rh-CO

298 K

333 K

353 K

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(1) Suzuki, A.; Inada, Y.; M.; Nomura, M.; Iwasawa, Y.et al., Angewandte Chemie Inter.Ed. 2003, 42, 4795.

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Illustrative mechanism and time scale at 298 K for the disintegration oRh clusters on Al2O3 during CO adsorption by time-resolved DXAFS

Species A Intermediate B Intermediate C Species D

CO CO CO

600 ms 2000 ms 4000 ms

17 kJ/mol

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(1) Suzuki, A.; Inada, Y.; M.; Nomura, M.; Iwasawa, Y.et al. Angewandte Chemie Inter.Ed. 2003, 42, 4795.

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Tada, M., S. Murata, et al. (2007). Angewandte Chemie-International Edition 46(23): 4310-4315.

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Electrochemical trigger

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IF we have faster XAFS, what will do we obtain?

s-s Reaction intermediate

at-fs

ps-ns Atomic Dynamics

Electron DynamicsPF-ERL

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July 6 2009 6WCOC31

Spectroscopy and desorption analysisT. Matsushima, Surf. Sci.Reports 52 (2003) ; Surf. Sci. 603 (2009) 1415.

diffusion

OCO

Surface

CO2

① ② ③

STMEn

ergy

Distance from the surfacevibration

Rotation

Angle, translation

Transition stateO,CO

①

②

③

Spectrscopy

Transition state

Repulsive desorption → No equillibrium and information after reaction is maintained.

O

④

Analysis of desorbed species transition state information

STM Spectrscopy

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CO2 Desorption profile during CO +O reactionT. Matsushima, Surf. Sci.Reports 52 (2003) ; Surf. Sci. 603 (2009) 1415.

0 30 60 900

500

1000

1500

T Tr

ansl

atio

nal /

K

/ deg

[11b0]

[001] Interaction is large.

Pd(110) surface

[001]

0]1[1

0]1[1

[001]

Angle dependence of Translation energy

θcos30]1[1

[001]θcos10

Fastest

Slowest

Pd(110)

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IR EmissionK. Nakao, K. Kunimori, et al. Catalysis Letters 85 (2003) 213; K. Nakao, K. Kunimori et.al., Catalysis Today 111 (2006) 316.

Position average of s and b

Symmetric stretch

Bending

ｓ mode

b mode

a mode Antisymmetric stretch

vibrational

rotation

RotationArea

Tva=2090 KTvsb=2200 KTr=1000 K

Anti-mode

IR emission from desorbed CO2 from Pd(111) with dirrerent surface temperatures

Surface temp=850 K

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Desorption from Pd(110)

Repulsive force

0 20 40 60400

600

800

1000

1200

1400

1600

1800

T vibration

[11b0]

T / K

Angle / Deg

[001]

T vibration

Large interaction

Coming along trough

Coming from the ridge

T. Yamanaka et al. Phys.Rev.Lett. 100(2008) 026104.

T surfacerotation

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Mmechanical catalystGerhard Swiegers

Energy –control to timing- control

Perfect Catalyst100 % acitivity, 100 % selectivity, Self-

recovery(long life time)Like Enzyme

Selective excitation

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Reaction induced by STM on Pd(110)

CH2CH2

CH3CH3

H2

Dosing tunneling current on7 nA, 450 mV, 1sec—C-H excitation.

Y. Sainoo, Y. Kim, M. Kawai, J. Chem. Phys.120 (2004) 7249.

Y. Kim, M. Kawai,et.al. PhysRev.Lett. 89 (2002) 126104.

-360 mV dI2/dV2 image

C-HC-D

T B

T

B

STS

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FEL-IR-selective excitation of chemical bond

H. Kuroda,et.al. Free Electron Lasers 2002, 2003, pp. II.

1. If one can use a strong pulse source with long interval, one irradiates the sample without heating the sample.

2μs

2sMacropulse

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July 6 2009 6WCOC 38

0.167 nm(967 cm-1)

0.173 nm (814 cm-1)

Ethanol decomposition reaction on MoO3 induced by Pulse IR

1.00 1.50 2.00 2.50 3.00 3.50 4.00 4.50 5.00

1.00 1.50 2.00 2.50 3.00 3.50 4.00 4.50 5.00

Ethylene

Ethylene

Aldehyde

1.00 1.50 2.00 2.50 3.00 3.50 4.00 4.50 5.00

Waterethanol

0.173 nm(814 cm-1)

1.9 mJ

3.2 mJ

3.5 mJ1230 cm-1

814 cm-1

967 cm-1

S.Sato, M.G.Moula Jpn.J.Appl.Phys. 41-1 (2002) 118; Chem.Lett 33 (2004) 558; Bull.Chem.Soc.Jpn., 81 (2008) 836.

No resonance

C2H5OH CH3CHO, CO2, C2H4

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Problems are

How to control inhomogeneity of CatalysisTime scale and Spatial scale. Chaotic reaction processSingle shot

CO oxidation reactions on Pt(100)

Surface is well-defined single crystal

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Real catalysts are complicated

Multifunctional Porus

Kapoor, M. P.; Inagaki, S. Bull. Chem. Soc. Jpn. 2006, 79, 1463.FSM-16

Moro-oka, Y. and W. Ueda (1994) Advances in Catalysis 40: 233.

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４D (Time + spatial resolution) +spectroscopyÅーmm の広いダイナミックレンジ ps- ms sub eV

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Conclusions

Ultra fast will help us understand the atom dynamics of surfaces

Ultrafast monitoring may be helpful to control the surface reaction

4D is necessary to apply the ultarafasttechnique to catalysts.

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