Catalytic steam reforming of biomass-derivatives for hydrogen production

Catalytic steam reforming of bio-ethanol and bio-tar for hydrogen production was studied. As for bio-ethanol steam reforming, Co-catalyst showed higher performance than others. Loading of 1-2 wt% K on Co/α-Al₂O₃ was effective for improving catalytic activity, hydrogen selectivity and suppressing byproduct (CH₄, C₂H₄, and coke) formations. TEM measurements showed that the Co0-CoO core-shell structure was formed over Co/K/α-Al₂O₃ during ethanol steam reforming at 823 K, suggesting that the oxidized Co species (CoO) is a highly active species in ethanol steam reforming. In-situ IR measurements revealed that the adsorbed ethanol forms stable acetate species by K loading, which improves hydrogen selectivity. Applying electric field to the catalyst bed enabled low temperature hydrogen production. Pt/CeO₂ catalyst showed high activity in an electric field even at 423 K. The supported platinum worked as an active site for the ethanol steam reforming. Ethanol conversion and H2 yield drastically increased with imposing the electric field, and apparent activation energies for three elementary reactions (ethanol dehydrogenation, acetaldehyde decomposition, and acetaldehyde steam reforming) were lowered by the electric field. For bio-tar steam reforming, Ni/perovskite catalysts showed excellent features including less coke formation. Ni/Al₂O₃ showed much coke formation, aggregated by oxidation or longer catalytic activity test, and lost its steam reforming activity by oxidation treatment. In contrast, Ni/La_0.7Sr_0.3AlO₃-d catalyst showed high and stable steam reforming activity even after the oxidation treatment. Ni particles on Ni/La_0.7Sr_0.3AlO₃-d retained the fine structure after oxidation treatment or reduction treatment.