A review of recent developments in hydrogen production via biogas dry reforming

Biogas is a promising renewable energy resource. Among the existing biogas utilization technologies, dry reforming can convert two major greenhouse gases in biogas, methane and carbon dioxide, into syngas. In this review, we summarize the recent advances in biogas dry reforming toward hydrogen production, including the preparation of catalysts, the optimization of operation conditions, and the influence of impurities in biogas. The development of bimetallic catalysts and core-shell structure catalysts has become increasingly attractive due to their high catalytic activity and stability. Choosing active metals, supports, and promoters for catalysts is systematically discussed, and different catalyst synthesis methods are compared. Solid waste-derived catalysts have been developed as a new approach to obtain a high added value of solid waste and reduce the costs of catalyst preparation. The influences of reaction temperature, pressure, calcination conditions, reduction conditions, and gas hourly space velocity on dry reforming reactions are discussed in detail. In addition to conventional fixed bed and fluidized bed reactors, several newer reactors are introduced, including membrane reactors, microreactors, and solar thermal flow reactors. Impurities in biogas such as hydrogen sulfide, oxygen, and siloxanes have significant effects on dry reforming. These effects are summarized to improve overall understanding of biogas dry reforming and to provide guidelines for its industrial application in hydrogen energy generation.