277607 Prediction of CO2 Adsorption Properties in Zeolites Using Force Fields Derived From Periodic Dispersion-Corrected DFT Calculations

Wednesday, October 31, 2012: 1:33 PM
405 (Convention Center )
Hanjun Fang1, Preeti Kamakoti2, Ji Zang1, Stephen Cundy2, Charanjit Paur3, Peter I. Ravikovitch3 and David S. Sholl1, (1)School of Chemical & Biomolecular Engineering, Georgia Institute of Technology, Atlanta, GA, (2)ExxonMobil Research and Engineering, Annandale, NJ, (3)ExxonMobil Research and Engineering Company, Annandale, NJ

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.

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See more of this Session: Molecular Simulation of Adsorption II
See more of this Group/Topical: Separations Division