Metal Phosphate-Supported Pt Catalysts for CO Oxidation.

Oxides (such as SiO₂, TiO₂, ZrO₂, Al₂O₃, Fe₂O₃, CeO₂) have often been used to prepare supported Pt catalysts for CO oxidation and other reactions, whereas metal phosphate-supported Pt catalysts for CO oxidation were rarely reported. Metal phosphates are a family of metal salts with high thermal stability and acid-base properties. Hydroxyapatite (Ca(PO₄)₆(OH)₂, denoted as Ca-P-O here) also has rich hydroxyls. Here we report a series of metal phosphate-supported Pt (Pt/M-P-O, M = Mg, Al, Ca, Fe, Co, Zn, La) catalysts for CO oxidation. Pt/Ca-P-O shows the highest activity. Relevant characterization was conducted using N₂ adsorption-desorption, inductively coupled plasma (ICP) atomic emission spectroscopy, X-ray diffraction (XRD), transmission electron microscopy (TEM), CO₂ temperature-programmed desorption (CO₂-TPD), X-ray photoelectron spectroscopy (XPS), and H₂ temperature-programmed reduction (H₂-TPR). This work furnishes a new catalyst system for CO oxidation and other possible reactions.