Nano bimetallic alloy of Ni–Co obtained from LaCoxNi1−xO3 and its catalytic performance for steam reforming of ethanol

Abstract

A novel preparation method for supported bimetallic alloy nanoparticles was investigated in this work. LaCo_xNi_1−xO₃ with perovskite structure was prepared according to the citrate complexing method. Metal Ni and Co could be obtained by reducing the perovskite precursors, and the characterization results from X-ray diffraction, temperature programmed reduction and transmission electron microscopy indicated that nanoparticles of Ni–Co solid solution alloy with size of around 12 nm were formed. As a lot of metal ions can enter into perovskite lattice, this method should be extended to prepare various bimetallic or polymetallic nanoparticles. The resultant catalysts of Ni–Co alloy supported on La₂O₃ presented high activity and good stability for steam reforming of ethanol. Carbon deposition and sintering of the metal nanoparticles were investigated. After 10 hours' running at the relatively low reaction temperature of 550 °C, Co-rich catalysts showed some deactivation, which was ascribed to carbon deposition. The cobalt sites in the catalysts were inclined to form amorphous carbon, while the nickel sites tended to generate filamentous carbon, and the former led to more severe deactivation. At the relatively high reaction temperature of 700 °C, the bimetallic alloy catalysts presented better anti-sintering ability than the monometal catalysts.