- 2:15 PM

Molecular Simulation of CO2 and CO2/CH4 Mixture Adsorption and Diffusion In Metal-Organic Frameworks

Jinchen Liu1, Seda Keskin2, Rees B. Rankin1, J. Karl Johnson3, and David S. Sholl2. (1) National Energy Technology Laboratory, 626 Cochrans Mill Road, Pittsburgh, PA 15236, (2) Chemical and Biomolecular Engineering, Georgia Institute of Technology, 311 Ferst Drive NW, Atlanta, GA 30332, (3) Department of Chemical and Petroleum Engineering, University of Pittsburgh, 1242 Benedum Hall, Pittsburgh, PA 15261

Capture of CO2 from large point sources such as fossil fuel power plants is important for mitigating global warming. Metal-organic frameworks (MOFs) and Zeolitic imidazolate frameworks (ZIFs) have been proposed as potential candidates for separating CO2 from gas mixtures. Adsorption and mass transport properties of MOF and ZIF materials for CO2 and CO2/gas mixtures are important in designing, screening, and applications of these materials. We have used grand canonical Monte Carlo simulations to calculate the adsorption isotherms for CH4, CO2 and their mixtures in MOFs and ZIFs. We have compared our mixture isotherms with predictions from the ideal adsorbed solution theory. We have computed the diffusivities for CH4, CO2 and their mixtures from equilibrium molecular dynamics simulations. We have predicted the mixed gas diffusion coefficients from SSK theory, and compared the SSK theory predictions with mixed gas diffusivities computed from equilibrium molecular dynamics. The molecular level information generated from simulations can be used to generate models for the performance of macroscopic membranes. The transport selectivity and permeance can be computed for a given set of conditions, leading to design calculations based on molecular simulations.