Hydrogen Production by Steam Reforming of Methane in Biogas Using Membrane Reactors with Dimethoxydimethylsilane-derived Silica Membranes Prepared by Chemical Vapor Deposition

Abstract

This work presents the development of membrane reactors to generate hydrogen by biogas steam reforming. The reactors consisted of Rh/Al₂O₃ catalysts and hydrogen-selective amorphous silica membranes that were prepared by the chemical vapor deposition of dimethoxydimethylsilane (DMDMS) with oxygen. Silica membrane application to such membrane reactors for the steam reforming of methane in biogas is novel. In the membrane reactors, hydrogen that is generated at the catalytic bed is expected to be extracted through the hydrogen-selective DMDMS-derived membranes immediately. This process intensification was effective, and the methane conversions always exceeded that using packed-bed reactors in which no hydrogen extraction occurred, even when the flow rate, the reaction temperature, and the model biogas composition varied. This behavior was due to hydrogen extraction through the DMDMS-derived membranes. We tested the membrane reactor stability by changing the composition of the model biogas every 6 h, and demonstrated that it showed excellent performance against the fluctuation of the feed composition from 50% methane with 50% carbon dioxide to 70% methane with 30% carbon dioxide. These results indicate that the developed membrane reactors are applicable for hydrogen production from biogas that is generated through the anaerobic digestion of organic matter.