Electrolysis of glycerol to value‐added chemicals in alkaline media

Abstract BACKGROUND Glycerol, a by‐product of biodiesel production, is produced in large quantities, exceeding its demand. The saturation of glycerol resulted in a sharp reduction in its market value and the surplus waste may pose a risk to the environment. By means of electrochemical technologies, glycerol could be oxidized into value‐added products such as glycerate, tartronate and lactate. In the present work, carbon‐supported NiBi catalysts with different atomic ratios (Ni x Bi 1− x /C, where x  = 100, 95, 90 and 50 at%) were fabricated and utilized in a 25 cm 2 electrolysis cell. RESULTS The as‐fabricated catalysts were characterized and analyzed by various physicochemical and electrochemical characterizations. Using a three‐electrode electrochemical cell, Ni 95 Bi 5 /C showed the highest current density of 104 mA cm −2 , with an onset potential of 1.32 V versus a reversible hydrogen electrode. Long‐term chronoamperometry was performed in a glycerol electrolysis cell accompanied by the product analysis using high‐performance liquid chromatography. It was found that Ni 95 Bi 5 /C had higher selectivity to glycerate C 3 product compared to Ni/C. Additionally, optimizing experimental conditions (applied potential, residence time and temperature) to achieve higher selectivity to C 3 products was thoroughly studied. The selectivity to C 3 value‐added products was enhanced by adjusting the operating conditions. CONCLUSION Small addition of bismuth to Ni/C enhanced both catalytic activity and selectivity to C 3 products. The main products formed on NixBi 1− x /C were formate and glycerate, while the secondary products were glycolate, tartronate, oxalate and lactate. By running electrolysis under optimal conditions, the selectivity to C 3 products was significantly enhanced. © 2022 Society of Chemical Industry (SCI).