Hierarchical approach for simulation of binary adsorption in silicalite

A hierarchical molecular modeling approach presented predicts adsorption th ermodynamics of single components and binary mixtures in zeolites. Atomisti c simulations that capture details at the molecular level are performed to calculate the free energies of molecules at discrete adsorption sites. Then a more coarse-grained lattice model is used to calculate the equilibrium l oading of adsorbates based on these free energies, and thermodynamic proper ties can be predicted. Sorbate-sorbate free energies beyond nearest-neighbo r interactions are introduced and their impact on the lattice model is inve stigated. By adding these free energies, the model is better able to accura tely describe single-component and binary adsorption of sulfur hexafluoride and neopentane in silicalite. The results from the lattice model agree wel l with full atomistic grand canonical Monte Carlo simulations performed for the same systems, but the hierarchical approach saves an order of magnitud e of computational effort.