High storage capacity and separation selectivity for C2 hydrocarbons over methane in the metal–organic framework Cu–TDPAT

Abstract

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.