Zeolite materials, which are widely used in the conversion and refining of petroleum derived hydrocarbons, are shape-selective molecular sieves that control catalytic reactivity on the basis of size exclusion. The focus of these zeolite materials has moved to produce renewable fuels and platform chemicals from alternate carbon feedstocks such as lignocellulosic biomass, especially in the thermochemical conversion processes in biorefineries. While chemical composition and atomic-layer reactivity is important in catalysis, mass transport through nanoporous materials (e.g. zeolites) can be a significant limiting factor in overall process kinetics. Our approach incorporates density functional theory (DFT), molecular dynamics (MD) simulations and mass transport characterization of biomass specific hydrocarbons diffusion, especially for designed zeolite and nanoporous catalytic structures. Our group establishes that the catalytic activity is studied at an atomistic scale by mechanistic studies using DFT and QM/MM. MD simulations are an effective approach to investigate coke precursor diffusions in hierarchical micro- and meso-porous zeolites which verify coking and other degradation mechanisms, while typical heuristic diffusion model overestimates the diffusion of bulky molecules in the mesopores.
Consideration of the Aluminum Distribution in Zeolites in Theoretical and Experimental Catalysis Research, Brandon C. Knott, Claire T. Nimlos, David J. Robichaud, Mark R. Nimlos, Seonah Kim†, Rajamani Gounder†, ACS Catal., 8, 770-784 (2018) [Online Article]
Diffusion of aromatic hydrocarbons in hierarchical mesoporous H-ZSM-5, Lintao Bu, Mark R. Nimlos, David J. Robichaud, Seonah Kim†, Catalysis Today, 312, 73-81 (2018) [Online Article]
Integrating Experimental and Computational Studies Unravels the Ga Species Responsible for Enhancing Alkene Production during Catalytic Upgrading of Biomass Pyrolysis Vapors over Ga/ZSM-5, Kristiina Iisa, Yeonjoon Kim, Kellene A. Orton, David J. Robichaud, Rui Katahira, Michael J. Watson, Mark R. Nimlos, Joshua A. Schaidle, Calvin Mukarakate†, and Seonah Kim†, Green Chem., 22, 2403-2418 (2020) (cover page, 2020 Green Chemistry Hot Articles) [Online Article]