Prediction of Adsorption Properties of Cyclic Hydrocarbons in MOFs Using DFT-Derived Force Fields

Abstract

We present an extension of previous methods that derive transferable force fields to describe the adsorption of small molecules in zeolites based on density functional theory (DFT) calculations to examine the adsorption of C 8 cyclic hydrocarbons in metal−organic frameworks (MOFs). We use our DFT-based force field to predict the adsorption properties of these molecules in MOFs where dispersion governs adsorption properties using grand canonical Monte Carlo (GCMC) simulations. We observe that DFT-derived force fields provide moderately more accurate predictions compared to generic force fields for single-component adsorption in these systems. We find that generic force fields can give qualitative agreement with experiments for binary selectivities, which could eventually be useful for materials screening purposes. We also assess the influence of factors such as framework relaxation due to guest adsorption on these calculations and find that these effects can produce significant changes in the simulated binary selectivities at high loadings. Our methodology will eventually be useful for developing force fields for systems in which generic force fields are known to fail and represent a useful step in understanding and predicting adsorption properties of C 8 hydrocarbons in MOFs.

DFT-based force field development for noble gas adsorption in metal organic frameworks

“…The derived FF was shown to be transferable to MIL-53 (Cr). Gee et al 38 derived DFT based FF to predict C 8 cyclic hydrocarbon adsorption properties in several MOFs having no open metal sites (MIL-47, DMOF-1, UiO-66 and IRMOF-1). The derived FFs surpassed generic FF performance of predicting heats of adsorption and adsorption isotherms slightly.…”

A Strong Test of Atomically Detailed Models of Molecular Adsorption in Zeolites Using Multilaboratory Experimental Data for CO2 Adsorption in Ammonium ZSM-5

“…This approach does not require experimental input, but some key factors that are responsible for the accuracy and reliability of the developed FFs need to be carefully taken into account, including the specific QM method, the functional forms used in the FF, and parametrization algorithms . This experiment-free approach has been applied to a wide range of molecular species adsorbing in zeolites and MOFs. ,− We previously used this approach to develop a FF based on dispersion-corrected plane wave DFT calculations with CCSD­(T) corrections for adsorption of CO 2 in siliceous and Na/K-containing zeolites. − Methods for making the latter corrections, which are assumed to be pairwise among atoms, were first introduced by Bludský, Nachtigall, and co-workers . The resulting FF, termed CCFF, accurately predicts experimentally observed adsorption properties and showed good transferability across different zeolite topologies.…”

Discovery of novel zeolites and multi-zeolite processes for p-xylene separation using simulated moving bed (SMB) chromatography

“…Granato et al (2014) evaluated four force fields for MOF UiO-66 and concluded that the estimation of absolute adsorption capacities can be different depending on the force field parameters for describing the electrostatic interactions, both for the single as well as for the multicomponent adsorption. Gee and Sholl (2015) proposed force fields based on density functional theory (DFT) calculations to examine the adsorption of C 8 cyclic hydrocarbons in several MOFs. However, xylene isomers are much larger molecules and no accurate force-field is currently available to predict the adsorption and diffusion of xylenes in zeolites, which limit the use of molecular simulation in our current framework.…”