Fabrication of a novel microporous membrane based on ZIF-7 doped 1,2-bis(triethoxysilyl)ethane for H2/CO2 separation

Abstract

The organosilica membranes for gas separation have been studied for approximately ten years, but the separation performance of the membranes is restricted by the trade-off effect. Therefore, the objective of this work is to design H2-selective mixed matrix membranes by combining the good thermal stability of organosilica and remarkable H2/CO2 selectivity of ZIF-7. Herein, we synthesized ZIF-7 nanoparticles with an average size of 60 nm and investigated the effects of ZIF-7 doping content on the separation performance of organosilica membranes. Interestingly, it absolutely was found that with the doping content of ZIF-7 increased, H2 permeance of ZIF-7/BTESE (1,2-bis(triethoxysilyl)ethane) membranes remained basically unchanged, whereas the permeance of larger molecular gases displayed a dramatically drop. The membrane, when the molar ratio of ZIF-7: BTESE = 0.2, showed the remarkable H2/CO2 (22.7) and H2/N2 (159) selectivity, with a comparatively outstanding H2 permeance at 8.0 × 10−7 mol m−2 s−1·Pa−1. Our results firstly reveal that the doping of ZIFs could be strongly influenced by ZIF-7 doping contents, emphasizing the importance of doping of ZIFs for the further studies on nanoparticles-doped BTESE-derived membranes.