Electrochemical biogas upgrading for high-value multiphase resource recovery via CO₂ conversion and sulfur-containing...

Biogas upgrading is essential for expanding biomethane utilization, but conventional separation-based technologies such as pressure swing adsorption, membrane separation, and chemical absorption often remove CO₂ and trace impurities without recovering their resource value. Electrochemical biogas upgrading offers a route to integrate gas purification with electrically driven CO₂ capture or conversion, impurity valorization, and multiphase product recovery. This review summarizes recent advances in electrochemical biogas upgrading from the perspective of gas-, liquid-, and solid-phase resource recovery. Gas-phase pathways include CH₄ enrichment, separated CO₂ recovery, CO production, and H₂-enriched fuel gases; liquid-phase pathways focus on the recovery of formate, acetate, and medium-chain fatty acids; solid-phase pathways recover elemental sulfur and mineral carbonates. Particular attention is given to route and configuration selection under realistic biogas conditions, including diluted CO₂, CH₄-rich backgrounds, sulfur-containing impurities, cathode-anode coupling, product separation, and downstream use. System-level sustainability and techno-economic drivers are further discussed, including electricity carbon intensity, product substitution, downstream separation, stack durability, and the comparability of published TEA/LCA assessments. Despite substantial laboratory-level progress, long-duration validation using real-biogas and standardized impurity-tolerance data remain limited. By aligning real-biogas operation, low-carbon electricity, and on-site reuse, electrochemical biogas upgrading may evolve from a CO₂ removal process into an integrated platform for biomethane production, impurity valorization, and circular water-energy-carbon management.