Hydrogen from electrochemical reforming of ethanol assisted by sulfuric acid addition

Abstract

The addition of H2SO4 to the anolyte feeding solution for the electrochemical reforming of ethanol has been studied in terms of activity and stability for hydrogen production in a PEM electrolysis cell. Five equivalent MEAs based on commercial Pt-Sn/C and Pt/C as anode and cathode materials, respectively, and a Nafion membrane, have been prepared and tested to optimize the addition of the H2SO4. Results demonstrated that the addition of an optimal H2SO4 concentration (ethanol 4 mol L−1 and 0.01 mol L−1 H2SO4) enhances the electrocatalytic activity and stability of the MEA by decreasing the energy requirements for hydrogen production. According to impedance spectroscopy experiments, this improvement is caused by a decrease in the anodic charge transfer resistance, probably due to an increase in the number of contact triple points (electrolyte/catalyst particles/electronic support). However, the addition of a higher H2SO4 concentration (0.05 mol L−1) induced the dissolution of the Pt-Sn/C anodic catalyst causing a severe degradation of the MEA. Therefore, the optimal addition of H2SO4, which is not consumed during the electrochemical reforming experiments, may be of great practical importance for using this technology for the renewable hydrogen production from real bioethanol streams.