Biogas Refining: A Review on Advances in Metal-Oxide-Modified Activated Carbon for H2S and CO2 Removal

This review provides a systematic analysis of advancements in biogas refining and biomethane purification, focusing on the application of biomass-derived activated carbon (AC) modified with metal oxides for the removal of hydrogen sulfide (H2S) and carbon dioxide (CO2). We explore technological innovations in biogas upgrading, including water scrubbing, pressure swing adsorption (PSA), membrane separation, and others, highlighting their operational efficiency, environmental impact, and cost-effectiveness. The removal of H2S and CO2 is critical in converting raw biogas, primarily composed of methane (CH4) and CO2, into high-purity biomethane, making it suitable for integration into existing natural gas infrastructures. Our findings underscore the potential of these new composite materials to enhance biogas upgrading technologies, fostering the broader use of biomethane as a sustainable energy source. Furthermore, this review offers valuable insights for the future design and optimization of these refining processes, positioning biomass-derived AC modified with metal oxides as essential in advancing the field of biomethane purification.