(159b) Molecular Simulation of Adsorption in Zeolitic Imidazolate Frameworks (ZIFs) for Gas Capture and Separation

The combustion of vast amounts of carbon-based fossil fuels, has led to one of the most serious global environment problems. Zeolitic imidazolate frameworks (ZIFs) are new class of materials that offer promising applications including highly selective separation and storage of CO2. The structure of ZIFs is based on tetrahedral network of zeolites in which the silicon is replaced by a transition metal and the oxygen by imidazolate. The study of the fundamental molecular mechanisms of CO2 uptake in ZIFs is crucial for guiding further optimization of these materials for gas capture and separation. Here, we report molecular simulation studies of CO2 and CH4 uptake behavior in a series of ZIFs based on the same zeolite topology with links that differ in their functionality. The adsorption calculations for CO2 and CH4 are in good agreement with experimental results. The magnitude of the contributions of electrostatic interactions in the adsorption of CO2 is found to correlate with the symmetry of the functionalization. The simulation results also show large contribution of the vdW interactions of the linker functional groups in the adsorption of CO2 and CH4 .