Computational study of the effect of organic linkers on natural gas upgrading in metal-organic frameworks

In this work a hierarchical multiscale approach combining grand canonical Monte Carlo simulation and density functional theory calculation was performed to study the effect of the chemical properties of nine organic linkers on CO2/CH4 mixture separation in metal-organic frameworks (MOFs). The computational results show that the organic linkers decorated with the electron-donating groups can strengthen the distribution of the electrostatic field in the pores of MOFs, and greatly enhance the adsorption selectivity of CO2/CH4 mixture in MOFs. This enhancement becomes stronger with the increase of the electron-donating ability of groups. In addition, this work also demonstrates that the negative steric hindrance effects on the separation behavior should be considered when the organic linkers are modified with multiple substitutions in designing new materials. The knowledge obtained is expected to provide useful information for tailoring the electrostatic properties of MOFs for separation of various gas mixture systems of practical importance. (C) 2009 Elsevier Inc. All rights reserved.