Low temperature hydrogen production by ethanol steam reforming over supported metal catalysts in an electric field

A novel electrocatalytic reaction system that involves catalytic reaction in an electric field, for low-temperature catalytic ethanol steam reforming using low-grade waste heat for H₂ production, was developed. The application of an electric field to Pt/CeO₂ catalyst enabled the reaction to proceed even at 423 K, at which a conventional catalytic reaction only slightly proceeded. Results of activity tests conducted using isotopes revealed that the electric field contributed to activation of the adsorbed OH_x species. In-situ DRIFTS measurements revealed that an electric field promoted the formation of reactive adsorbed intermediate acetate species and showed that the steam reforming reaction of the formed acetate species proceeded even at low temperatures. Results showed that ethanol steam reforming proceeded efficiently in the electric field at low temperatures. In this electrocatalytic reaction system, H₂ was produced efficiently from ethanol using less electricity, even at low temperature. Applying the electric field lowered the apparent activation energy of three elementary reactions, namely ethanol dehydrogenation, acetaldehyde decomposition, and acetaldehyde steam reforming. In particular, the electric field preferentially promoted acetaldehyde steam reforming. Energy demand for H₂ production in this electrocatalytic process was sufficiently low, at 79 MJ/kg H₂, which was about half of the combustion enthalpy of hydrogen.