Christopher L. Marshall Group Leader, Heterogeneous Catalysis Chemical Engineering Division

1. Heterogeneous Catalysis Research at Argonne National LaboratoryChemical Reaction Engineering Laboratory Washington University, St. Louis, MOOctober 24, 2006 Christopher L. Marshall Group Leader, Heterogeneous Catalysis Chemical Engineering Division CLMarshall@anl.gov

2. A + B  AB*  C E Reaction Coord. “A catalyst is a substance that promotes a chemical reaction with no net participation in it.” Berzelius, 1836 • The impact of catalysis on the nation's economy • Generate U.S. sales in excess of $400 billion per year. • Net positive balance of trade of $16 billion annually. • The fuel and chemical industry is a primary producer and consumer of energy. • > 90% of all chemical processes are catalytic. • Catalysis is essential • energy production • energy conservation • environmental maintenance and clean up

3. Chemistry Chemical Engineering Material Science Catalysis – Science Combining Three Disciplines Collaboration is not only key—it is ESSENTIAL Key Knowledge at the Interfaces

4. Goals of the Heterogeneous Catalysis Group • Develop fundamental understanding of the mechanisms of catalyst activity and deactivation. • Use new synthesis techniques to improve catalyst supports and active phases. • Develop new spectroscopic techniques for understanding catalysts under working conditions. • In situ characterization • Synchrotron x-rays • Interface with industrial and academic institutions to bring new techniques and technology into the market.

5. Current Catalysis Projects • Novel Nanoporous Membrane Catalyst for Selective Oxidation • Hydrocarbon Based NOx Reduction Catalysis • Ethanol Synthesis via Synthesis Gas Feed • 2 projects • New Nanoscale Fischer Tropsch Catalysts • Dense Membrane Catalysts for the Synthesis of Green Olefins • Microporous Membranes for the Purification of Hydrogen • Novel Nanoporous Membrane Catalyst for Selective Oxidation • Hydrocarbon Based NOx Reduction Catalysis • Ethanol Synthesis via Synthesis Gas Feed • 2 projects • New Nanoscale Fischer Tropsch Catalysts • Dense Membrane Catalysts for the Synthesis of Green Olefins • Microporous Membranes for the Purification of Hydrogen

6. Novel Nanoporous Membrane Catalyst for Selective Oxidation Christopher L. Marshall Stephanie Mucherie, Jeffrey W. Elam Peter C. Stair, Michael J. Pellin Lennox E. Iton, Larry A. Curtiss Hao Feng, Hsien-Hau Wang, Guang Xiong

7. Contact Control Identical Diffusion Paths Short Contact Time Reagent Size Control Pore-size Selection Site Isolation One site in each channel Barrier layers at ends Sequenced Sites Different sites at entrance/exit Reactants Products Reactants Intermediate Products Reactants Products Hydrophilic Hydrophobic Concept: Nanostructured Membrane Catalysis(nano monoliths)

8. Pore Growth Mechanism • E field assist dissolution of the barrier layer (effective only on the bottom of the pores) • Generation of new alumina barrier layer (on the Al/alumina interface) Field Assist Dissolution of the barrier layers

9. Pores Al2O3 porous layer The Porous Alumina Film G. Patermarakis, J of Catalysis147 141 (1994) AAO made in 0.3M oxalic acid

10. Whatman Anopore Membranes http://www.whatman.com

11. CH4 CH3 CH3 CH3 CH3 Al Al Al Al CH3 CH3 CH3 CH3 CH3 CH3 CH3 CH3 CH3 CH3 CH3 CH3 CH3 CH3 CH3 Al Al Al Al OH OH OH OH OH OH OH OH OH OH OH OH OH CH4 H2O H2O OH OH CH3 CH3 Al Al Atomic Layer Deposition (ALD) Trimethyl Aluminum (TMA) A) Al(CH3)3 Water B) H2O

12. Materials

13. Synthesis Strategy ALD Al2O3 ALD TiO2 ALD V2O5 AAO 40 nm pores deposit catalytic support shrink pores to 10 nm deposit catalyst ALD Viscous Flow Reactor

14. Coat Nanoporous Membrane with Al2O3 Using ALD Techniques L=50 mm 500 nm L/d ~ 103 d=65 nm Cross-Sectional SEM: Nanomaterials Research Corp. ALD Enables Extremely Conformal Coating Pore Diameter Control: ALD

15. ALD Results AAO 40 nm AAO pores Al2O3 on AAO 15 nm ALD film 40 nm AAO pores ZnO on AAO 15 nm ALD ZnO2 40 nm AAO pores Al2O3 on AAO 15 nm ALD film 40 nm AAO pores

16. Al ring around AAO as a supporter • Stable > 550°C • ΔP > 10 psi • Flow 10 sccm

17. C3H6 C3H8 COx Oxidative Dehydrogenation (ODH) of propane Formation of propylene but also undesired carbon oxides (CO and CO2) products • ODH rates on supported vanadium depend on • support composition • VOx surface density. • Increasing VOx surface density for all supports, • Activity , Selectivity to propylene  • Activity: • Polyvanadate > monovanadate Khodakov, A., B. Olthof, Bell, A. T., Iglesia, E. (1999). J. Catal.181: 205.

18. Objective • Study of the catalytic performance of VOx supported on AAO membrane • oxidative dehydrogenation of propane • Comparison with a conventional VOx/Al2O3 powder catalyst • Effect on the reactivity of the AAO membrane catalyst of • method of deposition • V loading • nature of the support oxide • activity & selectivity to propylene • Characterization of the supported vanadia species on the AAO membrane by XAS

19. 470 °C 500 °C 500 °C Conversion- Selectivity (%) VOx/Al2O3 Powder catalyst VOx/Al2O3/AAO Membrane catalyst Selectivity to propylene at 500°C: Membrane (60 %) > Powder (25 %) Selectivity improves moving to membrane

20. Selectivity to propylene (%) 1 ML V 8.5 V/nm2 2 ML V 14.5 V/nm2 2 ML V IWI 16 V/nm2 Selectivity For ~ V-loading • Selectivity to propylene: 2 ML VWI > 2 MLALD • V-loading: S (propylene) 80 % vs. 35 %

21. Activity (mol C3H8 converted.min-1.gV-1) Reaction temperature TiO2 Al2O3 Nb2O5 Support Effects Activity TiO2 > Al2O3 > Nb2O5

22. 1 ML ALD TiO2 7.5 V/nm2 1 ML ALD Al2O3 8.5 V/nm2 1 ML ALD Nb2O5 10 V/nm2 Selectivity to Propylene 530 °C Selectivity to propylene (%) Selectivity to propylene Al2O3 > Nb2O5> TiO2

23. Distance to Neighboring Atoms Type of Central Atom, Amount, and Oxidation State Number of Neighboring Atoms X-ray Absorption Fine StructureXAFS = XANES + EXAFS XANES EXAFS Type of Neighboring Atoms Absorption X-ray Energy (eV)

24. Gas Out Gas Flow Valves SS Flanges Gas In Thermocouple SS Sample Holder (~ 0.5 cm2) 1” Quartz Tube X-raypath Kapton Windows In Situ Cell Design • Design allows for wide range of reactive conditions • Temperature controlled to provide ramping and rapid temperature changes • Effluent gas can be monitored by GC, MS, etc. • Transmission or Fluorescence mode

25. 0.7 eV Al2O3 – 1c V2O5 Al2O3 – 2c V2O5 Al2O3 – 3c V2O5 TiO2 – 2c V2O5 Nb2O5 – 1c V2O5 ODH Membranes (XANES)

26. Conclusion • VOx/Al2O3/AAO membrane catalyst • Higher selectivity to propylene than conventional VOx/Al2O3 powder catalyst • 60 % vs. 25 % • For membrane catalyst prepared by ALD • ODH activity of propane increases as the VOx loading increases • Attributed to the formation of polyvanadates species (V-O-V bonds)

27. Conclusion • The selectivity to propylene depends on • Amount of V- loading • 1 ML ALD (80 %) > 2 ml ALD (35 %) • Method of Vanadium deposition • 2 ML VWI (63 %) > 2 ML ALD (35 %) • Chemistry of the support • Al2O3 (80 %) > Nb2O5 (55 %) > TiO2 (45 %). • The lower selectivity to propylene (Nb2O5 & TiO2) correlated to the pre-edge feature in the XANES spectra.

28. Questions ??