Enhancing syngas production from biogas: Combined steam and CO2 reforming over mechanochemically synthesized Ru/CeO2-Al2O3 catalysts

Abstract

Bi-reforming of biogas offers a sustainable pathway for producing syngas, a crucial precursor for fuels and chemicals. In this work, we demonstrate the efficacy of a scalable and environmentally friendly mechanochemical approach to synthesize Ru catalysts supported on CeO₂-Al₂O₃ mixed oxides. The catalysts' performance was evaluated in a fixed-bed reactor at 800 °C using a model biogas feed. Among the prepared catalysts, the 0.5Ru/CeO₂-Al₂O₃ variant demonstrated outstanding catalytic performance, achieving an initial CH₄ conversion of approximately 86 % and maintaining remarkable stability over 100 h of continuous operation. A comprehensive characterization campaign, including XRD, H₂-TPR, XPS, SEM, and HRTEM revealed that the mechanochemical synthesis promoted a strong metal-support interaction. This was evidenced by the formation of well-dispersed Ru nanoparticles in close contact with the support, leading to an increased concentration of Ce³⁺ species and enhanced catalyst reducibility. These properties are critical for facilitating the gasification of carbon deposits, thereby mitigating deactivation. Post-reaction analysis confirmed that coking was the primary cause of deactivation, with the more stable 0.5Ru catalyst showing a greater resistance to the formation of graphitic carbon. This research demonstrates the efficacy of the mechanochemically prepared Ru/CeO₂-Al₂O₃ catalysts for biogas bi-reforming and highlights carbon deposition as a critical challenge, underscoring the need for mitigation strategies to prolong catalyst performance.