Electrochemical conversion of lignin to short-chain carboxylic acids. Issue 8 (24th March 2023)

• Record Type: Journal Article
• Authors: Sun, Shirong; Qiu, Xueqing; Hao, Shuhua; Ravichandran, Sabarinathan; Song, Jinliang; Zhang, Wenli
• Is Part Of: Green chemistry. Volume 25:Issue 8(2023)
• Page Start: 3127
• Page End: 3136
• Publication Date: 2023-03-24
• Subjects: Environmental chemistry -- Industrial applications -- Periodicals; Environmental management -- Periodicals; 660
• DOI: 10.1039/d3gc00324h
• Languages: English
• ISSNs: 1463-9262

Abstract

Abstract : A method for direct electrochemical conversion of lignin to short-chain carboxylic acids is developed. Abstract : Lignin valorization is a challenge for chemical and materials scientists due to its complex molecular structure and intra- and inter-molecular assembly. Although catalytic conversion of lignin into small aromatic organic molecules has been widely investigated, it faces the problems of low selectivity and complex products. Herein, we report a direct electrochemical conversion method for the selective oxidation of industrial lignin to produce short-chain carboxylic acids (SCCAs) with a wide range of concentrations. In an electrolytic cell, lignin is chemically converted to SCCAs by H2 O2 with titanium silicate-1 (TS-1) as a catalyst. H2 O2 is generated in situ by the recombination of H + and HO2 − in a three-compartment cell by separately introducing hydrogen (H2 ) and oxygen (O2 ) as the sources of protons and HO2 − into the anode and cathode compartments. We have achieved a record-high concentration of SCCAs up to 109.8 mg mL −1 through the catalytic depolymerization of lignin. A high concentration of SCCAs of 80.1 mg mL −1 could also be achieved at a cell voltage of 2.13 V by coupling the 2e − -ORR and water oxidation using air and 1 M aqueous H2 SO4 solution as feedstocks. Our approach could eliminate the additional economic consumption and environmental hazards caused by the transportation and storage of commercially concentrated and stabilized H2 O2 . Aside from the SCCAs produced in this process, the formation of new carboxyl groups in the lignin residue during the oxidation reaction greatly broadens the application potential of industrial lignin.