Preparation of BTESE-derived organosilica membranes for catalytic membrane reactors of methylcyclohexane dehydrogenation

High-performance organic-inorganic hybrid silica membranes were developed for use in membrane reactors for methylcyclohexane (MCH) dehydrogenation to toluene (TOL). The membranes were prepared via sol-gel processing using bis(triethoxysilyl)ethane (BTESE). In particular, the effect of hydrolysis conditions (H2O/BTESE molar ratio) on membrane performance was extensively investigated. Characterization based on TO-MASS, FTIR, N-2 adsorption and positron annihilation lifetime (PAL) measurements of BTESE-derived silica gels revealed that the ethoxides of BTESE were almost completely hydrolyzed and the silica networks became dense by increasing the H2O/BTESE molar ratio from 6 to 240. BTESE-derived silica membranes showed a hydrogen permeance that was higher than 1 x 10 mol/ (m(2) s Pa). H-2/TOL selectivity increased from 100 to 10,000 by increasing the H20/BTESE molar ratio from 6 to 240, while keeping a hydrogen permeance of more than 1 x 10(-6) mol/(m(2)s Pa). In MCH dehydrogenation, a BTESE-derived silica membrane reactor with a Pt/gamma-Al2O3/alpha-Al2O3 bimodal catalytic layer achieved MCH conversion of 75% that was higher than the equilibrium conversion of 60%, and a hydrogen purity in the permeate stream of more than 99.9% at 230 degrees C. 2014 Elsevier B.V. All rights reserved.