(118g) Prediction of CO2 Adsorption Properties in Zeolites Using Force Fields Derived From Periodic Dispersion-Corrected DFT Calculations

We demonstrate a new approach to develop transferable force fields describing molecular adsorption in zeolites by combining dispersion-corrected Density Functional Theory (DFT) calculations and classical atomistic simulations. This approach is illustrated with the adsorption of CO₂ in zeolites. Multiple dispersion-corrected DFT methods were tested for describing CO₂ adsorption in Na-ferrierite. The DFT-D2 approach was found to give the best agreement with high level quantum chemistry results and experimental data. A classical force field for CO₂ adsorption in siliceous zeolites was then developed based on hundreds of DFT-D2 calculations that probed the full range of accessible volume in purely siliceous chabazite (Si-CHA) via random sampling. We independently performed experiments with Si-CHA measuring CO₂ isotherms and heats of adsorption by microcalorimetry. Excellent agreement was obtained between adsorption isotherms predicted with our first-principles-derived force field and our experiments. The transferability of this force field was examined using available adsorption isotherms for CO₂ in siliceous MFI and DDR zeolites, again with reasonably good agreement between calculated and experimental results. The methods demonstrated by these calculations will be broadly applicable in using molecular simulations to predict properties of adsorbed molecules in zeolites and other nanoporous materials.