Steam Reforming of Ethanol over Co/La_1-xSr_xBO₃ (B = Al, Cr, Mn, Fe) Catalysts

Abstract

The steam reforming of ethanol for producing hydrogen was evaluated over 5 wt% Co catalysts supported on perovskite-type oxides, La_1-xSr_xBO₃ (B = Al, Cr, Mn, Fe, x = 0-0.2) at 823 K with a molar H₂O/C₂H₅OH ratio of 6. Co/LaAlO₃ showed higher catalytic activity and stability than Co catalysts supported on LaCrO₃, LaFeO₃ and LaMnO₃. The molar La/Al ratio markedly affected the stability of Co/LaAlO₃ catalyst and a molar La/Al ratio of 1 was the most suitable, suggesting that the properties of the perovskite structure are important in the catalytic activity and stability. Partial substitution of Sr²⁺ for La³⁺ in LaAlO₃ resulted in further remarkable improvement of catalytic activity and hydrogen yield. We consider that enhanced mobility of lattice oxygen in La_1-xSr_xAlO_3-δ allows more frequent participation in the oxidation of intermediates over metallic cobalt, leading to both high catalytic activity and stability of Co/La_1-xSr_xAlO_3-δ in comparison with Co/LaAlO₃.