New parametrization of a Lennard–Jones force field based on Slater-Kirkwood correlation for computing adsorption on MOFs

Abstract

A new set of Lennard–Jones parameters to account the short interactions between atoms of MOFs and of guest molecules is proposed. The Slater‒Kirkwood relationship was used to obtain the LJ parameters for the framework atoms, so the proposed force set of parameters was named the Slater–Kirkwood force field (SKFF). GCMC simulations using SKFF were performed to predict the adsorption of CO₂, CH₄ and linear alkanes on several IRMOFs. The results predicted by SKFF were compared to those obtained by the traditional general force fields used in screening MOFs (UFF and Dreiding). The performance of the proposed SKFF was superior to those of the UFF and Dreiding force fields, without accounting electrostatic contributions. Additionally, the proposed set of parameters was able to accurately predict the adsorption behavior of binary (CO₂–CH₄, CO₂–N₂, CH₄–N₂) and ternary (N₂–CO₂–CH₄) mixtures on IRMOF-1 at 297 K. To evaluate the transferability of SKFF to other MOFs, the adsorption isotherms of CO₂, CH₄ and N₂ on UiO-66, UiO-67, DUT-52, CuBTC, MIL-100(Cr), MIL-47(V), ZIF-8 and ZIF-97 were also predicted. The results presented good agreement with the experimental data.