Microstructure, surface properties, and CO oxidation properties of oxidized Zr2Pd alloy glass

Abstract

Pd-dispersed composite catalysts were derived from amorphous Zr2Pd-based alloys; Zr65Pd35, Zr65Pd30Pt5, and Zr60Pd35Ce5 by heat treatment at 800 °C in air, and their CO oxidation reactivities were studied. The results of the X-ray diffraction (XRD) analysis indicated that the PdO phase mainly formed in the oxidized Zr65Pd35, and the metallic Pd phase formed in the oxidized Zr65Pd30Pt5 and Zr60Pd35Ce5. The scanning electron microscopic (SEM) images showed that the size of the Pd (PdO) particles increases by the addition of Pt or Ce into Zr–Pd metallic glass. The light-off CO oxidation reactivity and the frequency factor of oxidized Zr65Pd35 were higher than the others. This result was consistent with the amount of adsorbed CO, corresponding to the specific surface area of Pd phase. The CO oxidation reactivity was influenced not only by the morphology and the microstructure but also by the chemical state. Raman spectra and X-ray photoelectron spectra (XPS) indicated the existence of active oxygen species on the surface of Pd (PdO) particles in these catalysts. Thus, a novel type oxidation catalyst was achieved on the Pd-based materials by developing from amorphous alloy precursors and characterized by various methods.