Fundamental Insights into Walnut Shell Bio-Oil Electrochemical Conversion: Reaction Mechanism and Product Properties

The potential for electrochemical conversion of bio-oil was overlooked for a long period due to the poor electrical conductivity and unclear reaction mechanism. This study aimed to provide an insight into bio-oil of electrochemical conversion mechanism and product distribution. In this study, using walnut shell bio-oil with enhanced electrical conductivity by ammonium carbonate as raw material, electrolysis experiments were carried out using different electrolysis times by constant current method (20 mA) in H-type electrolytic cell at a stable temperature (0 °C). The results showed that phenols, aldehydes, and lignin were copolymerized; meanwhile, unsaturated fatty acids such as oleic acid underwent decarbonylation and decarboxylation. The hydrogen-releasing electrode reaction also occurred at the cathode during the conversion process. Besides, the properties of products were characterized by elemental analysis, GC-TCD/FID, GC/MS, 1 H NMR, FTIR, and TG-FTIR. Solid products were of possibility for application in new materials owing to containing copolymers with lignin structure, and gas products could be utilized as gas fuels with the combustible gas (H 2 , CO, CH 4 , and olefins) content as 79.24%. Graphical Abstract