Investigation of Biogas Dry Reforming over Ru/CeO₂ Catalysts and Pd/YSZ Membrane Reactor

The biogas dry reforming reaction offers a promising route for syngas production while simultaneously mitigating greenhouse gas emissions. Membrane reactors have proven to be an excellent option for hydrogen production and separation in a single unit, where conversion and yield can be enhanced over conventional processes. In this study, a Pd/YSZ membrane integrated with a Ru/CeO₂ catalyst was evaluated for biogas reaction under varying operating conditions. The selective removal of hydrogen through the palladium membrane improved reactant conversion and suppressed side reactions such as methanation and the reverse water-gas shift. Experiments were performed at temperatures ranging from 500 to 600 °C, pressures of 1-6 bar, and a gas hourly space velocity (GHSV) of 800 h^-1. Maximum conversions of CH₄ (43%) and CO₂ (46.7%) were achieved at 600 °C and 2 bar, while the maximum hydrogen recovery of 78% was reached at 6 bar. The membrane reactor outperformed a conventional reactor, offering up to 10% higher CH₄ conversion and improved hydrogen production and yield. Also, a comparative analysis between Ru/CeO₂ and Ni/Al₂O₃ catalysts revealed that while the Ni-based catalyst provided higher CH₄ conversion, it also promoted methane decomposition reaction and coke formation. In contrast, the Ru/CeO₂ catalyst exhibited excellent resistance to coke formation, attributable to ceria's redox properties and oxygen storage capacity. The combined system of Ru/CeO₂ catalyst and Pd/YSZ membrane offers an effective and sustainable approach for hydrogen-rich syngas production from biogas, with improved performance and long-term stability.