First-Principles Design of Coke-Resistant Dehydrogenation Catalysts for Valorization of Light Hydrocarbon Feedstocks

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The project will study the mechanism of poisoning of catalysts used to convert light hydrocarbon gases to higher value products. Specifically it will address coke formation - the process by which the hydrocarbons break down on the surface of the catalysts to form carbonaceous deposits that deactivate the catalyst. Mechanistic understanding will be derived from both theoretical predictions and experimental measurements, and will be used to predict, synthesize, and evaluate new catalyst formulations that are resistant to deactivation via coke formation. Poison-resistant dehydrogenation catalysts are needed to ensure effective utilization of the huge gas reserves associated with the Nation's shale resources. Efficient, durable, and economically attractive catalysts are essential for upgrading the light-gases to feedstocks of value to the energy and chemical sectors of the economy.The project will develop a fundamental understanding of the interaction between surface species and Pt-alloy dehydrogenation catalysts that give rise to their selectivity towards alkenes and for coke deposition during the high-temperature dehydrogenation of light alkanes. While the formation of the alkene has been studied, the mechanism of coke formation is unknown. Density Functional Theory (DFT) will be used to generate potential energy surfaces and kinetic activation barriers for the dissociation of alkanes to form carbonaceous surface species, thereby revealing how this mechanism is influenced by the electronic and geometric structure of the catalyst. Corresponding experimental studies will be carried out to understand the coking mechanism via analysis of the molecular fragments deposited on the catalyst surface. The insights from DFT and experimental characterization will be exploited to design new catalyst alloy structures and compositions with enhanced resistance to deactivation. Predicted designs will be experimentally validated by synthesizing the novel catalysts and testing their catalytic performance. Light alkanes, such as ethane and propane, produced as byproducts of hydrocarbon processing, and found naturally as minority components of natural gas, have little commercial value, and are sometime flared or burned only for their caloric value. Dehydrogenation of these hydrocarbons to their corresponding alkenes would produce higher-value intermediates especially attractive as chemical and polymer precursors. The results from this work will serve to build a diverse future chemical industry workforce through undergraduate chemical engineering curricula and recruiting of researchers from the diverse Rutgers undergraduate student body to contribute to the project.