Continuous Dual Hydrogenation of Biomass Substrates in a Membrane-Free Solid Electrolyte Reactor

Production of chemicals from biomass through electrocatalytic hydrogenation shows great potential to reduce environmental impact across various applications in sustainable materials, medicine, food, and more. Particularly, dual electrocatalytic hydrogenation, leveraging concurrent reactions at both anode and cathode stand out with maximized electron efficiency (∼200%) and production yield. However, at higher voltages, anodic hydrogen atoms (H^*) tend to revert to protons. This tendency results in challenges such as low conversion rates and selectivity, and difficulties in maintaining continuous production. Herein, by employing hydrazine and water as the hydrogen sources for anode and cathode reactions, respectively, we achieved efficient dual hydrogenation of maleic acid to succinic acid. This approach produces two H^* atoms per electron transferred, promoting effective carbon-carbon (C-C) bond formation at both cathode and anode. We further developed a modular, membrane-free solid electrolyte reactor for continuous dual hydrogenation of maleic acid using a commercial cobalt catalyst. By leveraging the hydrazine oxidation and water reduction, the reactor consistently produces succinic acid with a Faraday efficiency of approximately 180% for over 200 h at 100 mA. Our approach shows significant potential for practical applications in green chemistry, particularly in efficient biomass conversion.