Sustainable Adipic Acid Production via Paired Electrolysis of Lignin-Derived Phenolic Compounds with Water as Hydrogen and Oxygen Sources

Adipic acid (AA) is an important feedstock for nylon polymers and is industrially produced from fossil-derived aromatics via thermocatalysis. However, this process consumes explosive H-2 and corrosive HNO3 as reductants and oxidants, respectively. Here, we report the direct synthesis of AA from lignin-derived phenolic compounds via paired electrolysis using bimetallic cooperative catalysts. At the cathode, phenol is hydrogenated on PtAu catalysts to form ketone-alcohol (KA) oil with 92% yield and 43% Faradaic efficiency (FE). At the anode, KA is electrooxidized into AA on CuCo2O4 catalysts, achieving a maximum of 85% yield and 84% FE. Experimental and theoretical studies reveal that the excellent catalytic activity can be ascribed to the enhanced absorption and activation capability of reactants on the bimetallic cooperative catalysts. A two-electrode flow electrolyzer for AA synthesis realizes a stable electrolysis at 2.5 A for over 200 h as well as 38.5% yield and 70.2% selectivity. This study offers a green and sustainable route for AA synthesis from lignin via paired electrolysis.