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

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 La_1-yCe_yCo_0.87Pt_0.13O₃ 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 La_0.8Ce_0.2Co_0.87Pt_0.13O₃/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℃. The La_0.8Ce_0.2Co_0.87Pt_0.13O₃/SiO₂ catalyst performs well for CO oxidation even in the presence of 15% (volume ratio) H₂O and 12.5% (volume ratio) CO₂. Moreover, the oxide-modified platinum-cobalt nano-bimetallic catalysts display excellent stability with high resistance against sintering.