Cerium phosphate-supported Au catalysts for CO oxidation

Abstract

LaPO4 and hydroxyapatite (Ca10(PO4)6(OH)2) are typical metal phosphates recently found to be useful for making supported metal or metal oxide catalysts, but CePO4 (also belonging to the metal phosphate family) has been rarely used to make supported catalysts. It would be interesting to develop CePO4-supported catalysts and explore their catalytic applications. Herein, hexagonal CePO4 nanorods (denoted as CePO4-H), hexagonal CePO4 nanowires (CePO4-HNW), monoclinic CePO4 nanoparticles (CePO4-M), and monoclinic CePO4 nanowires (CePO4-MNW) prepared by different methods were used to support gold via deposition-precipitation with urea (DPU). The gold contents of these catalysts were all around 1 wt%. The catalytic activities of these Au/CePO4 catalysts in CO oxidation were found to follow the sequence of Au/CePO4-MNW > Au/CePO4-HNW > Au/CePO4-M > Au/CePO4-H. These catalysts were characterized by inductively coupled plasma-optical emission spectroscopy (ICP-OES), N2 adsorption–desorption, X-ray diffraction (XRD), transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), oxygen temperature-programmed desorption (O2-TPD), and CO2 temperature-programmed desorption (CO2-TPD) to find possible correlations between the physicochemical properties and catalytic activities of these catalysts.