Synthesis of highly hydrophobic and permselective metal-organic framework Zn(BDC)(TED)_0.5 membranes for H₂/CO₂ separation

Metal-organic frameworks (MOFs), as a newly developed family of crystalline microporous materials, have attracted considerable attention as promising candidates for the fabrication of superior molecular sieve membranes. For the synthesis of MOF membranes, the MOF's characteristics, such as pore size, stability, and adsorption affinity, have to be considered carefully. In this work, we prepare a highly hydrophobic and permselective Zn(BDC)(TED)_0.5 membrane for H₂/CO₂ separation through secondary growth method with seeding. Attributed to the preferential adsorption affinity and capacity to CO₂ as well as a highly porous structure with large channels, the Zn(BDC)(TED)_0.5 membrane displays a high H₂/CO₂ permselectivity. For the separation of an equimolar H₂/CO₂ mixture at 180°C and 1bar, a H₂ permeance of 2.65×10^-6molm^-2s^-1Pa^-1 and a H₂/CO₂ selectivity of 12.1 are obtained. Furthermore, because of its high hydrophobicity, the pore volume of Zn(BDC)(TED)_0.5 is not blocked in the presence of steam, which is promising for potential applications of hydrogen separation and purification.