Degradation of lignin to BHT by electrochemical catalysis on Pb/PbO₂ anode in alkaline solution

BACKGROUND Currently, renewable resources such as lignocellulose biomass are explored for valuable chemicals and biofuels. The study of conversion of lignin into valuable products is attracting increasing attention. Electrochemical oxidation has been used as an effective process for lignin degradation owing to its environmental friendliness and high efficiency. RESULTS Through analysis using XRD , SEM , and CV patterns, the self‐made Pb/ PbO 2 electrode is shown to have favorable properties as an anode for electrocatalytic degradation of lignin. The proposed sequence of reactions is illustrated for the electrochemical catalysis degradation of lignin to 2,6‐bis(1,1‐dimethylethyl)‐4‐methylphenol (BHT) on the Pb/ PbO 2 electrode surface. The optimum operating conditions for production of BHT (5.61 g L −1 ) from lignin degradation were found to be current density of 25 mA cm −2 and electrolysis time of 3 h. CONCLUSION A new process is proposed to degrade lignin to BHT in alkaline solution with a three electrode system consisting of a Pb/ PbO 2 working anode, a copper auxiliary cathode and a reference saturated calomel electrode. The sequence reactions for lignin to BHT suggest that the oxidization of lignin on the Pb/ PbO 2 electrode surface with the required amount of superoxide anion radical ( O 2 •− ) results in the effective breakage of the link between the hydroxyphenyl propane unit and benzene ring by the electrolysis.