Research

Our research focuses on the development and characterization of heterogeneous catalysts. Because these catalysts are used in the production of virtually all organic chemicals and fuels, as well as in many environmental applications, the study of these materials is an essential element in meeting the challenges facing chemical engineers.

One part of our research focuses on environmental catalysis. An example is the development of catalysts as part of a fuel processing system that will allow current fuels such as gasoline and diesel to be used to produce hydrogen for automobiles powered by fuel cells. These types of automobiles produce extremely low emissions and are more efficient than those based on combustion engines. There are significant catalyst and reactor design challenges that must be met, however. Catalysts must be active, selective for the specific reaction of interest, and deactivate at very low rates. We synthesize, test, and develop kinetic models for supported metal catalysts for reactions such as the selective oxidation of carbon monoxide, which purifies the hydrogen stream immediately upstream of the fuel cell. The demands of an automobile -compact reactor size, response to transient demands, and severe thermal cycles- also require innovative reactor design. We are working to find new ways of designing catalytic reactors to meet these demands.

Another example of environmental catalysis is the catalytic decomposition of nitric oxide, NO, which is present in engine exhausts and is an atmospheric pollutant. Although the decomposition of NO to nitrogen and oxygen is thermodynamically favored at the conditions present in exhaust gases, no practical catalyst has yet been developed that can carry out this reaction. Most catalysts are either poisoned by oxygen or deactivate rapidly in the presence of water vapor, which is also present in exhaust gases. We are carrying out research to understand the fundamental processes on the catalyst surface to help us develop a catalyst for this reaction. A second approach NO control is to catalytically oxidize NO to NO2, react this with a solid base to form a nitrate, and periodically pulse the nitrate with a reducing gas produced from the fuel. Though this is more complex than decomposing NO, this is one way to remove NO from exhaust gases. We are also studying materials for this process.

A second area of our research focuses on synthesis of chemical intermediates from simple carbon feedstocks such as methane. An example is the direct, stoichiometric synthesis of acetic acid from methane and CO2. This reaction has recently been demonstrated by one of our students. The low equilibrium yield of the reaction at all practical conditions, however, requires innovative approaches that will overcome this limitation, by reacting the acetic acid to further products, for example. The catalysts and reaction conditions for this synthesis reaction are being studied.

A final example that combines both types of catalysis is the synthesis of ultra-clean fuels using the Fischer Tropsch process. This process converts synthesis gas (a mixture of hydrogen and CO, derived from a number or feedstocks such as natural gas or coal) into liquid fuels. Although this process was originally developed a number of years ago, there are still significant research needs-including catalysts and reactor designs that maximize the yield of the desirable fuels and minimize the yield of low-value byproducts.

My research interests also include the application of the principles of heterogeneous catalysis to catalytic combustion, control of sulfur and nitrogen oxides from combustion processes, acid/base catalysis (e.g., for condensation reactions), hydrocarbon synthesis, and the study of catalyst deactivation.

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