Preparation and gas permeation properties on pure silica CHA-type zeolite membranes

Abstract

Pure silica CHA-type zeolite (Si-CHA) membranes were synthesized by a hydrothermal secondary growth method on porous α-alumina supports. Using Si-CHA seed crystals as a crystalline nuclei allowed the formation of a dense Si-CHA layer. The Si-CHA membranes prepared in this study showed excellent gas permeance derived from their large pore volume and effective molecular sieve performance for gas separation. The Si-CHA membranes exhibited excellent H2 and CO2 permeance of 1.1×10−6 and 1.7×10−6 mol/m2sPa, respectively. The ideal selectivity of H2/CH4 and CO2/CH4 were 34 and 54, respectively. The stability test in the presence of water vapor on the Si-CHA membranes was performed and the Si-CHA membranes demonstrated good water vapor resistance, more so than the topologically analogous aluminosilicate zeolite membrane (SSZ-13). The Si-CHA membranes were unlikely to present pore blockages by water adsorption because of their hydrophobic pore systems.