On-board hydrogen production in a hybrid electric vehicle by bio-ethanol oxidative steam reforming over Ni and noble metal based catalysts

In this work we present the optimisation of the oxidative steam reforming of ethanol for hydrogen production in order to feed a Solid Polymer Fuel Cell (SPFC) over a Ni-Cu/SiO2 catalyst at on-board conditions. The optimised experimental conditions involve a reforming temperature close to 700degreesC, a molar ratio of H2O/EtOH equal to 1.6 and a molar ratio of O-2/EtOH equal to 0.68. These conditions were also used to test noble metal (Pt, Pd, Ru and Rh) based catalysts. Ni and Rh based catalysts were tested in ageing experiments for up to 140 h at the optimised operating conditions. Ni-Cu/SiO2 and Rh/Al2O3 catalysts allowed a high hydrogen mixture as well as a constant selectivity to the reaction products, moreover the ethanol was totally converted during this time. In contrast, the Ni/SiO2 catalyst showed a continuous decrease in hydrogen production during ageing. An explanation to the differences between Ni and Ni-Cu catalysts is given in terms of the lower coke deposition on Ni-Cu catalyst due to the alloy formed. The rich hydrogen content in the outlet flow from the reformer obtained with the Ni-Cu, Ru and Rh based catalysts can be considered of high interest for fuel cells (FC) in mobile applications.