Understanding Liquid Phase Tandem Catalysis on Zeolite Encapsulated Metal Nanoparticles

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Biomass is becoming an increasingly important source of energy for the renewable manufacturing of fuels and chemicals. Biomass feedstocks are complex, however, and their conversion to high-value fuel and chemical products relies heavily on catalysis to accelerate chemical reactions and promote the formation of desired products. The project will explore novel catalyst designs that are capable of tandem catalysis, that is, catalysts structured such that they can carry out multiple reaction steps in a specific order in a single catalytic reactor. Tandem catalysis is more efficient and involves lower capital costs than traditional processes based on sequential reactors, which often carry the need for costly separation steps between reactors. To date, most research related to tandem catalysis has been done on a case-by-case basis targeting specific fuels or chemical products. This study focuses on developing generalized design guidelines that will promote faster and wider-scale adoption of tandem catalysis throughout the chemical manufacturing and fuel refining industries. The work will contribute to U.S. leadership in chemical and fuels manufacturing in areas as diverse as specialty chemicals, pharmaceuticals, and platform fuels and commodity chemicals.The overarching goal of the proposed work is to develop design principles for zeolite encapsulated metal (M@zeolite) catalysts to enable selective liquid phase tandem reactions, which include: 1) synthesize and characterize M@zeolite catalysts with controlled site density and distribution; 2) understand the solvent effect and the confinement effect in M@zeolite catalysts on rates and selectivities; and 3) establish correlations of the architecture, site distribution, and local environment of active sites with performance in tandem reactions. The project will leverage a novel cationic polymer assisted synthetic strategy to prepare M@zeolite catalysts, and characterize their properties and density of active sites with liquid phase techniques recently developed in the investigator's laboratory. In particular, the distribution of acid sites in the zeolite crystals of M@zeolite will be determined. The study will elucidate solvent and confinement effects on model liquid phase reactions over M@zeolite via a combination of kinetic and spectroscopic investigations by determining intrinsic activation energies. One-pot tandem reactions to upgrade furfural to C8 oxygenates/hydrocarbons, as well as pentanoic acid, will be employed as model reactions to investigate the impact of the density and distribution of acid sites in the zeolite crystal of M@zeolite on tandem catalytic processes and catalyst deactivation. On the educational front, the investigator will develop a program to introduce the basics of 3D printing technology to high school and undergraduate students as a hands-on activity to stimulate excitement about STEM related career opportunities, especially for students from underrepresented backgrounds.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.