“Strategy for Fabricating Nanoscale Catalytic Circuits”

Heterogeneous Kinetics and Particle Chemistry LaboratoryWashington University

St. Louis, Missouri

Graduate Students Undergraduate StudentsJohn Parai Joe SwisherEugene Redekop Adam GrimmXiaolin Zheng Yoonsung HanRebecca Fushimi* Zachary WegmannMike Rude* Amy Vukovich

Ana Brjetchkova*Graduated Jeffrey Packer

FacultyGregory YablonskyJohn T. Gleaves

“Strategy for Fabricating Nanoscale Catalytic Circuits”

Heterogeneous Kinetics and Particle Chemistry LaboratoryWashington University

St. Louis, Missouri

Why catalysis?

Why now?

What’s ahead?

TAP - International Research Applications1. Alternative energy sources: hydrogen production, synthesis gas, biomass conversion2. Environmental research: autoexhaust catalysis, NOx reduction, chemically benign processing3. Nanoscale research: catalytic nanofactories, atomic tailoring of particle surfaces4. Advanced industrial processes: high selectivity conversion of alkanes to useful chemicals

TAP Reactor System “Research World”(Temporal Analysis of Products)

Houston

Saint Louis

ChicagoNew Jersey

Bangkok

TokyoTokyo City

Beijing

Lausanne

Lund

Madrid

CardiffeBelfast

Lyon

DelftEindhoven

Ghent

BerlinBochum

LeipzigBarcelona

HKPCL - Washington University

Growing 2 systems/year

Catalysis Primer

Catalytic Cycle

Molecule A

Molecule B

MoleculesElectronsPhotons

Catalyst

StartRegeneration

A

B

A

C

Reaction

Photons,Electrons

AtomMoleculeEnzymeSimple,complex solid

D

A FewBenefits of Catalysis

LifeAmmonia fertilizerClean waterNontoxic auto-exhaustNylonSulphuric acid93 octane gasolineL-dopaHefty trash bagsAnti-freezeFuel cellsPlastic drain pipeAspartameRoundup and on and on ……

Catalysts give precise spatial and temporal control of chemical reactions,

can operate billions of cycles,

produce materials, fuels, agricultural and pharmaceutical products, and

store and release energy.

Some Current Challenges for Catalysis

Alkane conversion

1. Ethane CH3CHO (acetaldehyde)2. Ethane Aromatics3. Propane CH2 CHCHO (acrolein)4. Propane CH2 CHC N (acrylonitrile)5. Propane CH2 CHCH3 (propene)6. Propane CH2 CHCOOH (acrylic acid)

Photocatalytic Reactions

1. H20 + h Hydrogen2. CO2 + H2O + h Chemicals

C1 chemistry

1. CH4 + CO2 2CO + 2H2

2. CO + H2 Specific alkanes, alkenes3. CO + H2 CH3CH2OH, or higher

alcohol4. CO + H2O CO2 + H2

5. 2CH4 + O2 2CH3OH

Proven reserves - 1,200,000,000,000 barrelsCurrent rate of consumption - 80,000,000 barrels/day

(DOE, 2005)

Depletion of Oil - Current Estimates

Worlds Largest Oil Field

Ghawar Supergiant field- discovered 1948

Discoveries greater than consumption

Consumption greater than discoveries

Exploratory drilling

Depletion of Oil - Forecasting the Future

Fuel Imports ($ billions) % IncreaseEconomy 2000 2004 2000 - 2004

China 21 48 128India 19 34 79Japan 77 99 29US 140 216 54European Union 219 347 58

Projected consumption - 2010 - 91,000,000 barrels/day2015 - 100,500,000 barrels/day2020 - 110,300,000 barrels/day2025 - 120,900,000 barrels/day(DOE - Energy Information Adminstration 2004)

Depletion of Oil - Forecasting Future Demand

We are here

Population growth rates are predicted to continue to drop.

World population predicted to reach 9 billion by 2043.

Global Context in which New Technology is Developed

Where will the new people live?

Where do they obtain the raw materials for life?

food, water, fuel, ….

By 2050 the world populationwill reach 9 to 10 billion, and

current reservesof both oil and natural gas will

be exhausted.

(World Bank Statistics - 2004)

US World Low Income

GDP (US$) (billions) 11,711.8 41,365.8 1,216.0GNI per capita (US$/yr) 41,440.0 6,338.0 507.0

Life expectancy (years) 77.4 67.3 58.8

Population, total (millions) 293.7 6363.2 2311.7 Population growth (annual %) 0.8 1.2 1.8

Surface area (sq. km) (thousands) 9,629.1 133,940.9 29,264.5

In 2043World Population - 9,000,000,000US Population - 400,000,000

(US Census Bureau - 2006)

Where will the new people live?

Alternatives to PetroleumCoal, natural gas, oil shale, biomass

Syngas Process

CO + H2

Solar Catalytic ReactorCH4 + H2O 3H2 + CO

K.I. Zamaraev, Topics in Catalysis, 1996, 3,1.

The transition from petroleum will involve a change to a feedstock composed of C1 or C2 molecules and hydrogen.

Petroleum based chemistry - large hydrocarbon molecules are cracked into smaller molecules.

C1-C2 based chemistry - large molecules are assembled from small ones.

Changing Focus of Catalysis and Reaction Engineering

Highly selective catalysts to

perform multi-step reactions.

Industrial reactors that give

precise reaction control.

1. Multiple sites to perform different reaction steps.2. Molecular and nanoscale features.3. Complex and fragile. 4. Photocatalytic materials

Constructing Catalytic Circuits“Active Sites on a Chip”

Substrate surface

Thin film

C. Campbell, Surface Science Reports, 27, 1997, 1 - 111

Substrate surface

Metal cluster

Heiz, Sherwood, Cox, Kaldor, Yates, J. Phys. Chem. 99, 1995, 8730 - B. C. Gates, Chem. Rev. 95, 1995, 511 - 522C. Henry, Surface Science Reports 31, 1998, 231 - 325Iijima and Ichihashi, Phys. Rev. Lett. 56, 1986, 616 - 619

Ag nanocluster array on alumina

G. Rupprechter, A. Eppler, A. Avoyan, G. Somorjai, Studies in Surface Science and Catalysis, 130 (2000) 215 - 220

20 nm

Atomic Tailoring of Catalysts Particles

Precise Submonolayer Change in Surface CompositionPhysical characterization

Precise kinetic characterization

RH ROH

Metal OxideParticle

RH ROH

Oxygen, Metal atoms

Oxidation of a (VO)2P2O7 at Atmospheric Pressure

0

2

4

6

8

10

12

20 25 30 35 40 45 50

O2 desorption spectrumfrom 18O2-treated (VO)2P2O7

m/e

16O2

16O18O

18O2R

ela

tive

ion

si

gn

al

Single XRD phaseVanadium oxidation state = 4.02 Bulk Vanadium oxidation state = 4.1

VOPO4 phases may be present

(VO)2P2O7

Trx > 400, Pox ≈ 1atm, trx ≈ 1000 s

20

70

120

170

220

270

320

0 1000 2000 3000 4000 5000 6000 7000

Oxygen uptake behaviorSingle phase (VO)2P2O7 and (800 torr O2)

T= 460°C, V(4.13)

T= 430°C, V(4.07)

T= 450°C, V(4.10)

Oxy

ge

n u

pta

ke (

x10

17 O

ato

ms)

time (s)

12.7x1018 O atoms adsorbed

- O2

Vacuum

T> 400 °C

+ O2(VO)2P2O7

C4H10

Pulse

T = 380° CP = vacuum

Affect of Oxygen Surface Concentration on Catalyst Performance

C4H10 C4H2O3 (maleic anhydride)

O2

Flow

T = 480° CP = 1 atm.

0

20

40

60

80

100S

ele

ctiv

ity a

nd C

onve

rsio

n

R-Equil. 4-min.. 32-min. 64-min. 128-min.

Sel.

Con.

Oxygen treatment time

MA production versus VPO oxidation time

4-min. 32-min. 64-min. 128-min.Ox Time 0-min.

Increased oxygen concentration

New phase(VO)2P2O7

Metal OxideParticle

Atomically tailored surface compositionMetal atom deposition

Nanoparticles

Well-defined bulk lattice

Nanoscale Fabrication on Particles

+ MMMO

Metal-enriched nanolayer

MMO

Metal Atom Deposition on Metal Oxide Particles

Catalystparticles

OrganometallicCompound e.g., Ir6(CO)15

Chemical Vapor DepositionB.C. Gates, Chem. Rev. 95, 1995, 511 - 522.

ReactionProducts

Single Crystal

KnudsenCell

Atomic Beam

Atomic Beam Deposition

Creating Nanoscale Concentration Gradients of Transition Metal Species on Bulk Metal Oxide Catalysts

Transition metal source

Catalyst particle

Atomic beamLaser beam

Sample holder

(Vacuum - 10-8 torr)

Vibrate bed

Atom Deposition ChamberCu pulses

.1s

TC

Pulse

valve

Microreactor

Mass spectrometer

Catalyst

Vacuum (10-8 torr)

Reactant

mixture

TAP Pulse Response Experiment

Key Characteristics

Pulse intensity: 10-10 moles/pulse

Input pulse width: 5 x10-4 s

Outlet pressure: 10-8 torr

Observable: Exit flow (FA)

EEE

E

E

E

E

E

E

EEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEE

-10

0

10

20

30

40

50

60

70

80

0 0.5 1 1.5 2 2.5 3 3.5 4 4.5 5

E

E

E

E

E

EE

E

E

E

E

E

E

E

E

E

EE

E

E

E

E

EE

EE

EE

E

EEE

EE

E

E

E

E

E

EEE

E

E

E

E

EEEE

E

E

EE

E

EEE

E

EE

E

E

EE

EE

EEE

EE

EE

EEE

E

EE

EE

E

E

EEE

EEEEE

EE

EE

E

E

EE

EEEEEE

EEE

EE

E

E

E

E

E

EE

EE

E

E

E

EE

EEEE

EE

E

EE

E

E

E

EEEE

E

E

EEE

E

E

EE

EEEEE

EE

EEEEEEE

E

E

E

E

EEE

E

EEE

EE

EE

E

E

E

EE

E

E

E

EE

E

EE

EEE

E

E

E

EE

E

EEE

EE

E

E

EEE

E

E

E

E

EE

E

EEE

E

EE

E

EE

E

EE

E

E

EEE

E

EE

E

E

E

EEEE

E

E

E

E

E

EEE

EEE

E

E

EE

E

E

E

E

E

EE

E

EEE

E

EEE

EEEEEE

E

EEEE

E

E

E

E

EEE

E

E

E

E

EEE

E

E

E

EEE

E

E

EE

E

EEEE

EE

E

E

E

E

E

EEE

E

E

E

E

E

E

EE

EE

EE

E

EEE

E

E

E

EE

EE

EE

E

E

E

E

E

EE

EEE

E

EE

E

E

EE

E

E

E

E

E

EEEEEE

EE

E

E

E

E

E

E

E

E

EE

E

EE

E

E

E

E

E

EE

E

E

EE

EE

E

EEE

E

EEE

EEEE

E

E

E

E

EEE

E

E

EEEE

E

EE

E

E

EEE

E

EE

E

EEE

EE

E

E

E

EEE

E

E

E

EEE

E

E

E

EE

E

E

E

E

EE

E

EEEEE

E

EEE

E

EEE

E

EEE

E

E

E

E

E

E

E

EE

E

E

E

E

E

E

EE

E

EE

E

E

E

E

EE

E

E

EEEE

E

EEEE

E

EEEE

E

EEE

E

EEEE

E

E

E

E

EE

EE

EE

E

EE

E

EE

E

E

E

E

E

EE

EE

E

E

E

EE

E

E

E

E

EE

EEE

E

E

E

EEE

E

E

E

E

E

E

E

E

E

EE

E

E

E

E

EE

E

EEE

E

E

E

E

E

E

E

E

E

EE

E

E

E

E

EE

E

E

E

E

EE

E

E

E

EE

EE

E

EEEE

E

E

E

E

EE

EE

E

EEE

E

E

EE

EE

E

E

E

EE

EEE

E

E

E

E

EE

E

EEEE

EEE

E

EEEE

E

EE

E

E

E

E

EE

E

E

E

EEEEEE

EE

EE

EEE

E

E

EE

EE

E

E

EE

EE

E

EEEE

EE

E

E

E

E

E

E

E

EE

EE

E

E

E

EE

E

EEE

EEEEEE

E

-0.0025

0.0025

0.0075

0.0125

0.0175

0 1 2 3 4 5

.0025

time(s)5.0

5.0

80

2. Small pulse size - High S/N

ÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉ

ÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉ

ÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉ

ÉÉÉÉÉÉÉÉÉÉÉÉ

ÉÉÉÉÉÉÉÉÉÉÉÉÉ

ÉÉÉÉÉÉÉÉÉÉ

ÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉ

ÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉ

ÉÉ

É

É

É

É

É

É

É

É

É

ÉÉÉÉÉ ÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉ

ÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉ

ÉÉÉÉÉÉÉÉÉÉÉÉÉÉ

ÉÉÉÉÉÉÉÉÉÉÉ

ÉÉÉÉÉÉÉ

ÉÉÉÉÉÉÉÉÉÉÉÉÉÉ

ÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉ

ÉÉÉÉÉ

É

É

ÉÉÉÉÉÉÉÉ

-0.1

0.1

0.3

0.5

0.7

0.9

1.1

0.0 0.1 0.2 0.3 0.4 0.50.5time(s)

Argon

Butane Response after Reaction

Rel

ativ

e F

low

Experimental and Predicted ResponsesArgon and Butane Pulsed over VPO

EE

E

E

E

E

EEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEE

-2

0

2

4

6

8

10

12

14

16

18

0 0.05 0.1 0.15 0.2 0.25 0.3 0.35 0.4 0.45 0.5

Time (s)

Argon Pulse Response - Experiment vs Theory

Reactor Packing - InertQuartz Particles

ExperimentTheory

0.5time(s)

Nor

mal

ized

Flo

w

Experimental and Predicted Responses Argon Pulsed over Quartz Particles

440400

360320

280

Temp.time (s)

1.0

Rel

ativ

e

Inte

nsity

0.0

0.1

Experimental and Predicted ResponsesButane Pulsed over Oxygen-treated VPO

1.00

2.00

3.00

4.00

1.40 1.50 1.60 1.70 1.80 1.90

Arrhenius Plot Butane over Oxygen-treated VPO

1000/T

ln k

Ea = 12 kcal/mol

bCAt

DeA2CAz2

porosity effective

diffusivity

bCAt

DeA 2CAz2 kaCA

*

Transport + Irreversible Adsorption

1000

2000

3000

4000

5000

6000

10000

time(s)

PulseNumber

M0 Fexit (t )dt0

Zeroth Moment

Quantitative Determination of Catalyst Surface Composition and Kinetic Characteristics

• Conversion (number of surface

oxygen atoms and hydrocarbon)

• Selectivity

• Product Yield

• Residence time

• Apparent rate constants

• Apparent intermediate gas constants

• Apparent time delay

Quantities calculated from 0th, 1st, and 2nd moments

Shekhtman, S. Interrogative Kinetics A New Methodology or Catalyst Characterization. Doctoral Thesis, Washington University, 2003.

Atomic Beam Deposition of Pd on Silica ParticlesSilica particles

Pd/PdO deposits

Atomic Beam Deposition

Pd atoms

Sample holder

Laser spot

10-6 torr O2

TAP Experiments

CO CO2 O2 uptake

QMS Vacuum = 10-8 torr

TC

Steady-Flow Pulsed Input

Catalyst

Tubular Microreactor Vol = 0.33 cc

Inert Packing

Reaction Products

Slide Valve

0

1

2

3

4

5

6

7

8

9

0 500 1000 1500 2000 2500 3000 3500

Number of Laser Pulses

CO

2 P

rod

uct

ion

/O2

Up

take

TPR CO2 Production(x10 -̂17)O2 Uptake at RT(x10 -̂15)

- CO2 production

- Total O2 uptake at room temperature

Maximum indicates structure sensitivity

Kinetic Evidence of Reactive Self-assembly

Amorphous Pd/PdOdeposit

CO+ CO2

SiO2

Pd nanoclusters

Nanoscale Catalytic Circuit “Catalytic Nanofactory”

Example reaction: C3H8 + 2 O2 C3H4O2 + 2H2O

O2-n2

n4 O2

ne-

C3H8

H+ b+O2 activation site

C3H6C3H4O2Nanoparticle

mO24

Bulk phase (facile electron transfer)

Sub-surface phase (controlled oxygen transfer)

H2C CCH2

Insulatingphase

Ma MbSurface phase

Thanks for your attention.

Wavelength time (s)

"Reactor Equilibrated"(VO)2P2O7 1) Single XRD phase, 2) V oxidation state = 4.02

1 atm O2 470 ° C, 60 min.

Vacuum 535° C, 30 min.

“Oxygen Treated” VPO C4H10

MA

0

50

100

150

200

5390 5410 5430 5450 5470 5490-1

0

1

2

3

4

0 0.2 0.4 0.6 0.8 1

VOPO4

C4H10

MA

0

50

100

150

5390 5410 5430 5450 5470 5490-1

0

1

2

3

4

0 0.2 0.4 0.6 0.8 1

Vacuum Transformation of Oxygen-treated (VO)2P2O7

0.0 1.0 2.0 3.0 4.0 5.0

20

40

60

80

100

Fexit (t)

Fexit (t) t (x5)

Fexit (t) t 2 (x10)

time (s)

Primary and Time-weighted Transient Response Curves

M0 Fexit (t )dt0

M1M0

Fexit (t )tdt

0

M0res

M2M0

Fexit (t )t

2dt0

M0

(0th moment)

(1st moment)

(2nd moment)

EEE

E

E

E

E

E

E

EEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEE

-10

0

10

20

30

40

50

60

70

80

0 0.5 1 1.5 2 2.5 3 3.5 4 4.5 5

E

E

E

E

E

EE

E

E

E

E

E

E

E

E

E

EE

E

E

E

E

EE

EE

EE

E

EEE

EE

E

E

E

E

E

EEE

E

E

E

E

EEEE

E

E

EE

E

EEE

E

EE

E

E

EE

EE

EEE

EE

EE

EEE

E

EE

EE

E

E

EEE

EEEEE

EE

EE

E

E

EE

EEEEEE

EEE

EE

E

E

E

E

E

EE

EE

E

E

E

EE

EEEE

EE

E

EE

E

E

E

EEEE

E

E

EEE

E

E

EE

EEEEE

EE

EEEEEEE

E

E

E

E

EEE

E

EEE

EE

EE

E

E

E

EE

E

E

E

EE

E

EE

EEE

E

E

E

EE

E

EEE

EE

E

E

EEE

E

E

E

E

EE

E

EEE

E

EE

E

EE

E

EE

E

E

EEE

E

EE

E

E

E

EEEE

E

E

E

E

E

EEE

EEE

E

E

EE

E

E

E

E

E

EE

E

EEE

E

EEE

EEEEEE

E

EEEE

E

E

E

E

EEE

E

E

E

E

EEE

E

E

E

EEE

E

E

EE

E

EEEE

EE

E

E

E

E

E

EEE

E

E

E

E

E

E

EE

EE

EE

E

EEE

E

E

E

EE

EE

EE

E

E

E

E

E

EE

EEE

E

EE

E

E

EE

E

E

E

E

E

EEEEEE

EE

E

E

E

E

E

E

E

E

EE

E

EE

E

E

E

E

E

EE

E

E

EE

EE

E

EEE

E

EEE

EEEE

E

E

E

E

EEE

E

E

EEEE

E

EE

E

E

EEE

E

EE

E

EEE

EE

E

E

E

EEE

E

E

E

EEE

E

E

E

EE

E

E

E

E

EE

E

EEEEE

E

EEE

E

EEE

E

EEE

E

E

E

E

E

E

E

EE

E

E

E

E

E

E

EE

E

EE

E

E

E

E

EE

E

E

EEEE

E

EEEE

E

EEEE

E

EEE

E

EEEE

E

E

E

E

EE

EE

EE

E

EE

E

EE

E

E

E

E

E

EE

EE

E

E

E

EE

E

E

E

E

EE

EEE

E

E

E

EEE

E

E

E

E

E

E

E

E

E

EE

E

E

E

E

EE

E

EEE

E

E

E

E

E

E

E

E

E

EE

E

E

E

E

EE

E

E

E

E

EE

E

E

E

EE

EE

E

EEEE

E

E

E

E

EE

EE

E

EEE

E

E

EE

EE

E

E

E

EE

EEE

E

E

E

E

EE

E

EEEE

EEE

E

EEEE

E

EE

E

E

E

E

EE

E

E

E

EEEEEE

EE

EE

EEE

E

E

EE

EE

E

E

EE

EE

E

EEEE

EE

E

E

E

E

E

E

E

EE

EE

E

E

E

EE

E

EEE

EEEEEE

E

-0.0025

0.0025

0.0075

0.0125

0.0175

0 1 2 3 4 5

.0025

time(s)5.0

5.0

80

Small Pulse Size - High S/N

Insignificant change

time0.0

Experimental Features of TAP Pulse Response Experiment

Activity- Structure Relationship for Complex Catalysts

Catalyst Preparation Methods

from

“Methods for Preparation of Catalytic Materials”,

C. Contescu, and A. Contescu, Chem. Rev. 1995, 95,47

Key Results:

Metal Atom Deposition Experiments

• Demonstrated a new approach for adding metals atoms to the surface of a bulk metal oxide.

• Shown that small changes in the metal atom surface concentration can influence reaction kinetics.

• Changes can be detected using transient response experiments.

Oxygen Titration Experiments

• Catalyst selectivity changes as a function of the catalyst oxidation state.

• Total amount of catalyst oxygen used: 7.7 1018 atoms

5.5 atoms O/molecule Furan

9.5 atoms O/molecule Butane

8 atoms O/molecule Butene

7.8 atoms O/molecule Butadiene

• Total amount of catalyst oxygen used: 7.7 1018 atoms

• Oxygen consumption = oxygen adsorbed during oxidation treatment.

• Apparent Kinetic Constants

Reactants • was greatest for butadiene.

Products • indicated different reaction paths.

• was linearly independent of oxidation degree

suggesting a more complex supply mechanism.

V2O5 + o-H3PO4 (100%) isobutanol

(reflux 16h)Catalyst precursor (1)

Single XRD phase: (VO)2P2O7

Vanadium Ox. State: 4.01 - 4.02

Air/butane (1.5% C4)

1 bar, 673 K, t > 1000h.

Dry

Air calcine(1) (2)

Bulk Catalyst Preparation for Butane Oxidation

Phase B

Surface phase

Catalytic Selective Oxidation-Reduction CycleR. K. Grasselli, Surface properties and catalysis by nonmetals, 1983, 273 -288

Ma Mb

O2-n2

n4 O2

n e-

Propane

Acrylic acid

H+

a+ b+

C3H8 + 2 O2 C3H4O2 + 2H2O

Selective oxidation of propane to acrylic acid

Propaneactivation

site

Oxygenactivation

site