High storage capacity and separation selectivity for C2 hydrocarbons over methane in the metal–organic framework Cu–TDPAT†
We report on the storage capacity and separation selectivity of an rht-type metal–organic framework, Cu–TDPAT [TDPAT = 2,4,6-tris(3,5-dicarboxylphenylamino)-1,3,5-triazine], for C2 hydrocarbons over CH4. Henry's constant, the isosteric heat of adsorption and the ideal adsorbed solution theory selectivity were calculated based on single-component sorption isotherms. Theoretical calculations indicate that both the open metal sites and the Lewis basic sites have strong interactions with the C2 molecules. The combination of these two kinds of sites lead to the highest C2H2–CH4 selectivity of 127.1 as well as record high values for C2H4 adsorption enthalpies. To mimic real-world conditions, breakthrough experiments were conducted on an equimolar four-component mixture containing C2H2, C2H4, C2H6 and CH4 at room temperature and 1 atm pressure. Our results show that Cu–TDPAT is a promising candidate for CH4 capture and purification.