Characterization and transport properties of surfactant-templated silica layers for membrane applications

An intermediate surfactant-templated silica (STS) layer is applied between the supporting mesoporous gamma-Al2O3 and the amorphous microporous silica overlayer resulting in dual-layered microporous silica membranes for gas separation applications that show improved values for both hydrogen flux and selectivity. Determination of thickness and porosity of as-deposited membrane layers by spectroscopic ellipsometry reveals that the STS layer is present as a distinctive layer of sim20 nm thickness, with penetration up to a depth of sim70 nm into the underlying gamma-Al2O3support layer, whose thickness and porosity are determined to be 1.3 mgrm and 50%, respectively.