Influence of the anolyte feed conditions on the performance of an alkaline glycerol electroreforming reactor

Abstract

This manuscript presents the results of an alkaline glycerol electroreforming reactor for the production of hydrogen mounted in an alkaline membrane fuel cell. Commercial PtRu/C and Pt/C were used as catalysts in the anode and cathode, respectively, with a KOH-doped polybenzimidazole (PBI) membrane. The influence of the fuel composition (a glycerol and KOH solution) and the flow rate were studied to assess the electrochemical performance, hydrogen yield, and efficiency compared to the values predicted by Faraday’s law. The best conditions for cell performance corresponded to 2 mol L−1 glycerol, 4 mol L−1 KOH, and a fuel flow rate of 1 mL min−1, which yielded a hydrogen production close to that dictated by Faraday’s law. Moreover, potassium glycerate and tartronate could be obtained as the main added-value products from the glycerol electrooxidation, with minor amounts of mesoxalate, oxalate, glycolate, and formate. In general, more oxidized products, especially potassium tartronate, are favored at low glycerol and high KOH concentrations. A preliminary analysis of the energy consumption indicated lower requirements compared to a KOH-doped PBI alkaline water electrolysis system, although the performance was limited by the low current densities (and concomitant hydrogen yield rate) that could be obtained. Finally, stoichiometric calculations demonstrate that the hydrogen obtained could be used for biodiesel hydrogenation to improve its properties while still maintaining a surplus of hydrogen.