Preparation of La-Ce oxide-modified platinum-cobalt nano-bimetallic catalysts with perovskite-type composite oxides as precursors and their performance in CO oxidation

Abstract

A new scheme for constructing composite catalyst composed of oxide-modified bimetallic nanoparticles was proposed, where perovskite-type oxide (PTO) is utilized to confine multifold metal ions in the perovskite crystal lattice. With a perovskite-type oxide (PTO) of La1−yCeyCo0.87Pt0.13O3 loaded on large surface area SiO2 as the precursor, where the La, Ce, Co and Pt ions were uniformly mixed and confined in the PTO crystallites, a series of Pt-Co/La-Ce-O/SiO2 catalysts were prepared through reduction. The Pt-Co/La-Ce-O/SiO2 catalysts were characterized by nitrogen physisorption, XRD, H2-TPR and TEM; their catalytic performance in CO oxidation was investigated. The results indicate that La-Ce-O-Pt-Co clusters are constructed on the SiO2 surface, forming platinum-cobalt nano-bimetallic particles after reduction; the modification of Pt with Co can enhance the catalytic activity and the addition of Ce can further improve the catalytic performance in CO oxidation. The La0.8Ce0.2Co0.87Pt0.13O3/SiO2 catalyst with y = 0.2 (representing the Ce content) exhibits high activity in CO oxidation; over it, a complete conversion of CO can be achieved at 120°C. The La0.8Ce0.2Co0.87Pt0.13O3/SiO2 catalyst performs well for CO oxidation even in the presence of 15% H2O and 12.5% CO2. Moreover, the oxide-modified platinum-cobalt nano-bimetallic catalysts display excellent stability with high resistance against sintering.