(569u) Solvent-Induced Active Site Mobilization and Local Electric Field Effects in Lewis Acid-Containing Zeolites

The solvent plays a key role in controlling the performance of liquid-phase zeolite-catalyzed reactions by influencing the local electric field and microenvironments around active sites. Solvents in zeolite can be difficult to model because they can adopt a wide range of configurations in the pores and around metal active sites, resulting in a high computational cost to sample all possible structures. We tackle this challenge by first developing a method to relate local electric field strength to solvent structure within the zeolite pores, then applying the electric field correction to study reactions of interest without having to model all of the solvent molecules explicitly. To develop this method, we first use molecular dynamics simulations to determine the local electric field strength of a given solvent, using styrene oxide (SO) isomerization on Sn-BEA zeolites (Sn framework sites) as a model reaction. This reaction was selected because it has a large difference in dipole strength between the reactant and transition state, meaning changes in the local electric field strongly impact the activation barrier. Computed SO activation barriers are shown to vary with field strength, and the fields are then mapped to corresponding solvents for comparison to experimental data. We then extend this method to metal-exchanged Co-zeolites, where the extraframework Co ions can traverse the zeolite and experience a wider distribution of local environments and effective fields. The impact of this research illuminates how solvents impact catalyst reactivity and selectivity in industrial processes such as biomass valorization, plastics upcycling, and sustainable production of aviation fuels.