Fabrication of Hydrogen-Selective Silica Membranes via Pyrolysis of Vapor Deposited Polymer Films

Efficient separation of hydrogen under steam reforming conditions is important for the development of clean energy sources. Although high-temperature and steam-stable membranes with high fluxes and large separation factors would be valuable for such an application, their fabrication remains a challenge. Silicon-based ceramic membranes are particularly promising due to their high temperature resistance and excellent chemical stability. In this study, we propose a new synthetic route for fabricating nanoporous, asymmetric membranes via the pyrolysis of silicon-containing polymer films deposited by initiated chemical vapor deposition (iCVD) on macroporous silicon carbide supports. Specifically, we systematically investigated the change in the chemical structure of poly(2,4,6,8-tetravinyl-2,4,6,8-tetramethyl cyclotetrasiloxane) films at different pyrolysis temperatures and found that the complete transition to a silica membrane occurred at ∼1100 °C. Three different supports composed of silicon carbide powders...