Adsorption isotherm sensitivity to small changes in zeolite structure

Grand canonical Monte Carlo (GCMC) simulations of benzene adsorption in different ortho silicalite structures are analyzed to determine the origin of a surprising factor of 3.1 difference in the Henryʹs law constants. Results indicate that changes of only tenths of هngstrِm in the lattice oxygen atom positions can reposition the sorbates enough to sizably affect the electrostatics. The small shifts are magnified by the partial cancellation of large electrostatics terms on the hydrogen and carbon atoms. These results underscore the need for potential models that include lattice flexibility and polarizability when the sorbates are tightly fitting, as well as accurate crystallographic structures.