CO2/CH4, CH4/H2 and CO2/CH4/H2 separations at high pressures using Mg2(dobdc)

Abstract High-pressure separations of binary and ternary mixtures of CO 2 , CH 4 , and H 2 are relevant to carbon dioxide capture as well as hydrogen and natural gas purification. Metal–organic frameworks represent a class of porous materials that could be used to accomplish these separations, and Mg 2 (dobdc) (dobdc 4−  = 1,4-dioxido-2,5-benzenedicarboxylate), also sometimes referred to as Mg–MOF-74 or CPO-27–Mg, is an especially lightweight metal–organic framework with a high concentration of coordinatively-unsaturated metal sites decorating its interior surfaces. High pressure CH 4 adsorption isotherms presented here, together with CO 2 and H 2 adsorption behavior, are analyzed using the Ideal Adsorbed Solution Theory to model CO 2 /CH 4 , CH 4 /H 2 , and CO 2 /CH 4 /H 2 mixture separations using Mg 2 (dobdc). The selectivities, working capacities and breakthrough performances for these three mixtures are reported, and Mg 2 (dobdc) is shown to outperform zeolite 13X in each scenario.