Contact InfoEmail: firstname.lastname@example.org
Office: 172 Fitzpatrick Hall
Summary of Activities/Interests
Assistant Professor, University of Notre Dame (1975-1979)
Associate Professor, University of Notre Dame (1979-1985)
Visiting Researcher, Exxon Research Development Labs, Baton Rouge (1983)
Professor, University of Notre Dame (1985-present)
Visiting Scientist, Istitute de Recherches sur la Catalize, Lyon, France (1990)
Visiting Scientist, Instituto Polutecno de Valencia, Spain (1997)
Visiting Professor, Caltech (1997)
Visiting Scientist, Universita de Bologna, Bologna, Italy (2005)
Anthony Earley Professor of Energy and the Environment (2013)
B.S. Civil and Chemical Engineering, University of Chile (1969)
M.S. Chemical Engineering, University of California, Davis (1972)
Ph.D. Chemical Engineering, University of California, Berkeley (1975)
Heterogeneous catalysts are used in 90% of chemical processes in the chemical and petroleum industries as ell as in environmental applications. Research in our group focuses in the rational design of novel catalytic materials and novel catalytic reactors. The research approach combines experimental techniques involving advanced high throughput catalysts evaluation techniques, with spectroscopic techniques to characterize the surface and the adsorbed intermediates involved in the reaction (See fig. 1) with theoretical simulations of reactions' pathways. High throughput experimentation includes infrared thermography followed by evaluation in a ten-channel parallel flow reactor. The most active catalysts is studied in detail by kinetics measurements, surface analysis, and microscopic techniques to determine the structure and composition of the surface. Characterization includes scanning probe microscopy (STM, AFM),, x-ray photoelectron spectroscopy (XPS), x-ray diffraction, x-ray absorption fine structure (EXAFS), and gas adsorption. The above information is used to develop a model of the surface that is integrated into either an elementary reaction model or in a Monte Carlo simulation to develop a structure-activity correlation and synthesize new catalysts based on this knowledge.
Current research projects are focused in the catalysis for the production and purification of hydrogen for fuel cells. Hydrogen is produced by catalytic reforming of hydrogen bearing molecules, such as methanol or hydrocarbons (fig. 2), and needs to be purified via the selective oxidation of carbon monoxide without oxidizing hydrogen. We are studying such reaction on new interfacial metal-oxide catalysts that are active and selective at low temperature. We are also studying the generation of hydrogen via the catalytic partial oxidation of methanol in a replaceable cartridge for small fuel cells. A novel method for catalysts preparation involving combustion synthesis is being developed in collaboration with Prof. A. Mukasyan.
Another line of research focuses on the partial oxidation of alkanes to olefins using a new membrane reactor that can operate under autothermal and safe conditions for oxidation reactions. Studies involving the rational design of new selective catalysts by high throughput methods and modeling the membrane reactor are underway for the partial oxidation of propane to acrolein.
A further advanced project involving the microfabrication of supported catalysts is underway with Oak Ridge National Laboratories.
V Subramanian, R. Roeder and E.E. Wolf. Synthesis and UV-visible- Light Photoactivity of Noble-Metal-SrTiO3 composites. Ind. Eng. Chem. Res., 45:2187-2193, 2006. The photocatalytic activity of strontium titanate (SrTiO3) perovskite films has been examined and compared with commercially available titania (TiO2, Degussa P25) towards the degradation of a model pollutant, Victoria blue dye. The effects of the pH, synthesis temperature, and Sr:Ti ratio were examined. Noble metal substituted SrTiO3 was prepared using Ag, Pt or Au and characterized using optical and surface analysis methods. Ag substituted SrTiO3 showed the most promising catalytic activity towards dye degradation. Degradation of the dye under visible light (l > 400 nm) was observed only for Ag substituted SrTiO3.
C.O'Neil and E.E. Wolf. Yield improvement in Membrane Reactors for Partial Oxidation Reactions. Ind. Eng Chem Research, 45:2697-2706, 2006. Implementing a distributive membrane reactor for partial oxidation reactions, specifically the oxidative dehydrogenation (ODH) of propane and the partial oxidation (POx) of propylene to acrolein, is the focus of this theoretical investigation. The reactor model in this study demonstrates that the membrane reactor increases the yield of the desired product, propylene or acrolein, while suppressing the yield of COx. The membrane reactor accomplishes this by lowering the partial pressure of a reactant, oxygen, to suppress the full oxidation reaction that has a higher order dependence on oxygen. In addition to improvements for these individual reactions, the reactor model is expanded to include two different catalyst beds, the ODH reaction and the POx reaction. The dual-bed membrane reactor design improved the yield of acrolein compared to a dual-bed fixed bed reactor. The distributive membrane reactor is a useful tool to further enhance the performance of these POx catalysts.
S. Schuyten and E.E. Wolf. Selective combinatorial studies of Ce and Zr promoted Pd-Cu/Zn catalyst for hydrogen production via oxidative reforming of methanol. Catalysis Letters, 106:7-14, 2006. The activity and selectivity for partial oxidation of methanol to H2 and CO2 on Zr, Ce, promoted Cu/Zn/Pd catalysts, have been studied using a high throughput method of screening and analysis. In this work, infrared thermography was first used as a descriptor of overall catalytic activity. Then, activity and selectivity of samples with high infrared signal were measured in a flow reactor and characterized by BET, XRD, and XPS. Catalysts promoted with 10% Zr and showed H2 selectivity >95% with methanol conversion approaching 100% at ~200°C.
F. Gracia, J. Miller, J. Kropf , and E.E. Wolf. In-situ FTIR, EXAFS, and activity studies of the effect of SO2 on Pt/Al2O3 catalysts during CO oxidation. J. Catalysis, 233:372-387, 2005. The effect of the presence of sulfur over the state of the catalytic surface during oxidation reactions on supported Pt catalysts has been investigated by kinetic studies and operando infrared (IR) and in-situ extended X-ray absorption fine structure (EXAFS) spectroscopies. The experimental results clearly show that the catalytic surface is not static and the reaction atmosphere strongly affects the state of the surface and consequently the catalytic activity. The activity results show that the light-off temperature for CO oxidation increases with ex-situ H2S addition. In-situ IR results show a shift of the linear CO band indicating a change in the bonding of adsorbed CO due to the presence of sulfur. Continuous co-feeding of 20 ppm of SO2 with the reactant mixture also increases the light-off temperature. Activity and IR results demonstrate that alumina acts as a sulfur storage reservoir. This delays the initial deactivation but after extended time on stream in presence of SO2 the activity of the silica- and alumina-supported catalysts is similar. The results indicate that sulfur poisoning is not only due to blocking of the sites where oxygen preferentially adsorbs but also because of modification of the Pt-CO bonding.
A.P Wieber and E.E. Wolf. An STM study of phosphoric acid inhibition of the oxidation of HOPG and carbon catalyzed by alkali salts. Carbon, 44:2069-2079, 2006. The role of phosphoric acid as an inhibitor in the oxidation of HOPG and as a neutralizer of alkali salt catalysts is examined using scanning tunneling microscopy, supported by thermogravimetric analysis of carbon powder samples. HOPG samples were oxidized in air primarily at 700 ºC, with a few samples oxidized at 800 ºC. Reaction time was 20 minutes. Powder samples were oxidized for 5 minutes at temperatures ranging from 500 – 900 ºC and rates of oxidation were determined. STM images of impurity deposits and oxidized samples are presented and analyzed. Two alkali salts are examined, sodium hydroxide and potassium acetate, and both catalyze oxidation at 700 ºC. Phosphoric acid proves to be an inhibitor at 700 ºC but begins to lose its inhibiting effect at 800 ºC. It also demonstrates neutralization of potassium acetate at 700 ºC but results for NaOH/phosphoric acid mixtures are less conclusive