Coke formation and its impacts during electrochemical upgrading of bio-oil

Abstract Electrocatalytic hydrogenation is a potential means to upgrade bio-oil under mild working conditions. Here we report the formation of a carbonaceous solid (coke) on the surface of the electrode and its impacts during the electrochemical upgrading of bio-oil. The electrolytic experiments were conducted under the condition of 200 mA cm−2, 25 °C, and ambient pressure. As the electrolytic experiments progressed, the aromatic structures in the bio-oil were decreasing, while the radicals were increasing in their types and concentrations. The aromatic structures in the bio-oil were polymerized to form coke with heteroatom-containing radicals. The coke-covered electrode would enhance the oxidation process and inhibit the transformation of the aromatic structures in bio-oil. Moreover, the heteroatom-containing radicals contained in the initial coke would further enhance the coke formation. Last, an initial strategy was reported to remove the coke deposited on the surface of the electrode during the electrochemical upgrading of bio-oil.