(147b) Understanding Hydrocarbon Reactivity In Zeolites with Molecular Dynamics Simulations

First principles simulations in zeolites reveal the principles of elementary catalytic reactions that are not captured by experiment. One such methodology for molecular dynamics simulations is quantum mechanical/molecular mechanical (QM/MM) simulation, which greatly improves computational efficiency. Although many such techniques exist, our method does so with little sacrifice in accuracy by systematic choice of MM parameters. This methodology is utilized to simulate short time kinetics involved in hydrocarbon conversions in zeolites. These trajectories can provide estimates of carbocation lifetimes, and we will describe dynamics studies of the tert-butyl carbocation in H-FER and H-MFI zeolites. The simulations provide estimates of the lifetime of this important intermediate, and these will be compared to lifetimes obtained from transition state theory.