Designing microporous catalysts to overcome material and reaction limitations

Michele L. Sarazen

Department of Chemical and Biological Engineering, Princeton University, Princeton, NJ, 08544

With the ubiquity of catalysts in industrial processes for chemical, fuel, polymer, and pharmaceutical production, catalyst design that limits deactivation and improves efficacy (in terms of mass transfer artifacts and/or selective conversions) can decrease process energy demands. Our work focuses on porous crystalline materials such as zeolites and metal-organic frameworks (MOFs), where it is important to define active sites, to probe influences of transport, and to incorporate deactivation and materials stability. In the case of zeolites, incorporation of mesopores into bulk microporous frameworks is one route to alter mass transfer, particularly of bulky molecules. Here, we probe the condensed-phase hydrocarbon conversions (aromatics and waste polyolefins) on various microporous and hierarchical zeolites to deduce diffusional effects on rates, selectivities, and stability using kinetic analyses and observed changes in reaction and deactivation rates. We show that while reactivity and selectivity are highly sensitive to subtle nuances in pore structure and connectivity, deactivation trends via coke collapse as functions of surface area, mesopore volume, and extent of reaction. In the case of MOFs, the less hydrothermally stable counterpart to zeolites, we delineate structural and reaction stability during liquid-phase reactions, specifically over the Cr and Fe variants of MIL-101 for styrene oxidation by hydrogen peroxide. Overall, we demonstrate that deactivation phenomena limit catalyst efficiencies in both zeolitic and MOF reaction systems but can be alleviated through synthetic and reaction modifications, which has broad implications for these and other industrial catalytic systems.

Michele L. Sarazen is an Assistant Professor in the Department of Chemical and Biological Engineering at Princeton University. Her research group couples synthetic, kinetic, and theoretical investigations of porous crystalline materials as catalysts and adsorbents for sustainable fuel and chemical production with an emphasis on reaction and deactivation mechanisms. She earned her BS in Chemical Engineering, summa cum laude, at the Pennsylvania State University and her PhD in Chemical Engineering from the University of California, Berkeley. Before arriving at Princeton, she was a postdoctoral fellow at the Georgia Institute of Technology. Her recognitions include the NSF CAREER Award, AIChE 35 under 35, ICC Young Talent Laureate, Howard B. Wentz, Jr. Junior Faculty Award, National Academy of Engineering Frontiers of Engineering, The Catalysis Review “Mover and Shaker”, and MSDE Outstanding Early Career Paper Award. She has served as a Division Director and D&I Task Force member for AIChE in Catalysis and Reaction Engineering, Director of the Catalysis Society of Metropolitan New York, Early Career Board member for Journal of Catalysis and Applied Catalysis A, and ACS CATL Division Program Chair.