Influence of the intermediate layer on the hydrothermal stability of sol-gel derived hybrid silica membranes

摘要

The hydrothermal stability of microporous silica hybrid sol-gel derived membranes is often only tested for either the mesoporous intermediate membrane layer or the microporous separation layer. In this work an investigation is done on the interaction between the intermediate gamma-alumina layer and the hybrid (BTESE-derived) silica separation layer during hydrothermal treatment. Although bare gamma-alumina is degraded during a hydrothermal treatment, a coating of hydrophobic BTESE on gamma-alumina retains its gas separation performance, albeit with a lower mechanical adhesion between the hybrid silica separation layer and the gamma-alumina intermediate layer. Applying a monoaluminumphosphate (MAP) coating between the alpha-alumina support and the gamma-alumina layer stabilizes the gamma-alumina membrane. A BTESE coating on a MAP modified gamma-alumina membrane did not show any signs of delamination after hydrothermal testing. Moreover, a significant increase in the H-2/N-2 (perm)selectivity, factor 3, was observed for these membranes. (C) 2017 Elsevier Ltd. All rights reserved.