Tuning the microstructure of organosilica membranes with improved gas permselectivity via the co-polymerization of 1,2-bis(triethoxysilyl)ethane and 1,2-bis(triethoxysilyl)methane

Abstract

1,2-bis(triethoxysilyl)ethane (BTESE)-derived membranes have proven thermal and hydrothermal stability and molecular sieving properties. However, BTESE-derived membranes still have low gas permselectivity due to their loose structure. Herein, we propose a novel strategy of co-polymerization using precursors of both BTESE and 1,2-bis(triethoxysilyl)methane (BTESM) to improve the gas permselectivity of BTESE-derived membranes. BTESM is introduced into BTESE network and the microstructure can be adjusted by different molar ratios of BTESE to BTESM. We find that, as the content of BTESM increase, H2 permeations of BTESE-BTESM membranes remain nearly constant, while the permeations of larger gases (CO2 and N2 etc.) exhibit a greatly decreased. The membrane with a molar ratio of BTESE:BTESM = 3:7 exhibits the highest H2/CO2 (11.3) and H2/N2 (26.8) permselectivity while having a relatively high H2 permeance (1.52 × 10−6 mol m2 s−1⋅Pa−1). Our findings may provide novel insights into preparation of co-polymerization organosilica membranes with excellent H2/CO2 and H2/N2 separation performance.