A new MOF-505@GO composite with high selectivity for CO2/CH4 and CO2/N2 separation

Abstract

Novel MOF-505@GO composites comprised of a copper-based metal-organic framework and graphite oxide (GO) were synthesized by a solvothermal method for effective separation of CO2/CH4 and CO2/N2, which are challenging chemical separations in industry. The composites were characterized by various techniques including powder X-ray diffraction (PXRD), scanning electron microscopy (SEM) and porosity measurement through nitrogen adsorption at cryogenic temperature. Single component adsorption isotherm measurements of CO2, CH4 and N2 were performed at different temperatures. The selectivities of CO2/CH4 and CO2/N2 were estimated on the basis of ideal adsorbed solution theory (IAST). MOF-505@GO composites showed higher porosity and enhanced CO2 adsorption compared to its parent compound MOF-505. MOF-505@5GO exhibited the highest CO2 uptake of 3.94mmol/g at 298K and 100kPa, having an increase of 37.3% in comparison with the parent MOF-505. The significant improvement of CO2 uptakes could be attributed to not only new micropores and unsaturated metal sites formed in the MOF-505@GO, but also enhanced surface dispersive forces of the composites. The experimental adsorption isotherms of CO2, CH4 and N2 were well fitted with dual site Langmuir-Freundlich (DSLF) model. The CO2/CH4 and CO2/N2 adsorption selectivities were up to 8.6 and 37.2 at 298K and 100kPa, respectively, predicted by IAST. More strikingly, the composites showed excellent moisture stability, which was confirmed by PXRD analysis. These superior performances suggested that the MOF-505@GO composites are promising candidates for industrial CO2 capture.