Continuous caustic aqueous phase electrochemical reforming (CAPER) of ethanol for producing compressed hydrogen

Abstract

Caustic Aqueous Phase Electrochemical Reforming (CAPER) of ethanol produces pure compressed H2 at lower voltages, temperatures, and energy requirements than conventional electrolysis, while capturing carbonaceous products. The CAPER flow reactor consists of stainless steel endplates, stainless steel current collectors, and a Teflon flow field. The electrodes are prepared using commercial palladium nanoparticles on carbon support for the anode and platinum nanoparticles on carbon support for the cathode. The catalyst metal loading was 1 mg cm–2 on a 10 cm2 carbon cloth for both electrodes. Our CAPER reactor produces pure H2 at 80 bar and 80 °C applying voltages at ≤0.5 V. The only gas-phase product detected was H2 and any carbonaceous products were contained in the liquid phase. The H2 was produced with 97 ± 4% faradaic efficiency. Operating at smaller electrode separation distances (4 mm) and 80 °C increased the current density. The highest lower heating value efficiency achieved was 28% at a flow rate of 0.05 mL min–1 and an applied voltage of 0.5 V. The compressed H2 was produced at ≤20 kWh kg–1, which is much lower than electrolysis systems that require upwards of 50 kWh kg–1.