Preparation of Highly Active, Low Au-Loaded, Au/CeO2 Nanoparticle Catalysts That Promote CO Oxidation at Ambient Temperatures

摘要

In this work, highly active, low Au-loaded CeO2 nanoparticle catalysts were prepared by several solution chemistries and studied for low-temperature CO oxidation applications. Structures of the CeO2 nanoparticles and the resulting Au/CeO2 catalysts were characterized by X-ray diffraction, transmission electron microscope, X-ray photoelectron spectroscopy, and UV-vis diffuse reflectance spectra. The CeO2 support had a surface area of 120 m~2/g and had particle sizes that ranged from 9 to 15 nm. The large surface area of the particles and their fine sizes allowed high dispersion of Au species over the CeO2 support. Conversion of CO to CO2 with the catalyst was significant (ca. 80%) at 0 °C and complete (100%) at 20 °C for a Au loading of 0.52 wt %, demonstrating efficient low-temperature oxidation. Chemical species present in the Au/CeO2 catalyst were Au~0, Au~+, and Au~(3+), in which Au~+ acted as the dominant active species. During the catalytic reactions, Au~(3+) was probably reduced to Au~+, which enhanced the catalytic oxidation of CO.