CAREER: Molecular imprinting strategy to rationally design porous solid acid catalysts for C-C coupling chemistries

Colorado School Of Mines, Golden CO

Investigators

Abstract

Catalysts have long been used to enhance the rate of chemical reactions, improve energy efficiency, and direct reactions toward desired products. Zeolites are a class of nanoporous solid-acid catalysts that are particularly well suited to reactions of hydrocarbons derived from natural gas and petroleum resources. The transition from fossil-based resources to bio-renewable feedstocks in recent years has triggered interest in modifying zeolites and other microporous catalysts to increase their effectiveness for reacting raw biomass molecules to higher-value fuels and chemicals. The project investigates a novel approach for modifying acid catalysts that involves promoting reaction rates through confinement in tight spaces while facilitating diffusion of bulky product molecules away from the active sites. The approach utilizes a molecular imprinting atomic layer deposition method to create microporous silica structures near the active sites to induce confinement effects without imposing transport constraints. These solid acids catalysts with tunable porous structures will be tested for their effectiveness and stability in aromatic alkylation and aldol condensation reactions, chosen because of their widespread application in industrial chemistry and in upgrading biomass-derived molecules. The project will involve strong coupling between research and education by integrating the research results into classroom materials, providing research opportunities for students from historically underrepresented groups in STEM, showcasing the investigator’s laboratories to local K-12 female students, and creating and broadcasting educational videos via social media channels for researchers who are new to heterogeneous catalysis research. Over the last two decades, the field has made significant progress in understanding the effects of reaction network, kinetics, and transport on observed rates, selectivities, and stabilities, on chemistries occurring on confined spaces such as microporous acidic zeolites. Yet, the three-dimensional network of microporous structures in zeolitic materials often introduces unwanted transport effects that can lead to undesired side reactions and catalyst deactivation caused by pore blockage. This project aims to add another dimension in rationally designing porous materials by developing and implementing molecular imprinting atomic layer deposition methods to create microporous SiO2 architecture near active sites in mesoporous aluminosilicates to induce confinement effects without imposing transport constraints. These solid acids with tunable porous structures will be used to assess their detailed role on observed rates, selectivities, and stabilities by combining kinetic, spectroscopic, and theoretical methods. In doing so, this proposal aims to provide comprehensive catalyst design principles for active site manipulation that match the specific requirements of C-C coupling chemistries. 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.