Au/Ce0.6Zr0.3Y0.1O2 Nanorods: Highly Active Catalysts for the Oxidation of Carbon Monoxide and Toluene

Abstract

The Ce0.6Zr0.3Y0.1O2 (CZY) nanorods and its supported nanosized gold (xAu/CZY, Au loading (x) = 0.4–4.7 wt %) were prepared using the cetyltrimethylammonium bromide-assisted hydrothermal and polyvinylpyrrolidone-protected reduction methods, respectively. Physicochemical properties of the samples were characterized by means of numerous analytical techniques, and their catalytic activities were evaluated for the oxidation of CO and toluene. It is shown that the CZY in xAu/CZY was cubic in crystal structure, surface areas of CZY and xAu/CZY were in the range of 68–79 m2/g, and the Au nanoparticles (NPs) with a size of 3.1–3.9 nm were well dispersed on the surface of CZY nanorods. Among the xAu/CZY samples, the 4.7Au/CZY sample possessed the highest adsorbed oxygen concentration and the best low-temperature reducibility, and showed the highest catalytic activity at a space velocity of 20 000 mL/(g h): the T50% and T90% (temperatures required for achieving reactant conversions of 50 and 90%) were 32 and 60 °C for CO oxidation and 218 and 265 °C for toluene oxidation, respectively. Deactivation of water vapor addition was reversible, a result due to the competitive adsorption of H2O and toluene as well as oxygen on the sample surface. The apparent activation energies (27–37 and 39–53 kJ/mol) obtained over xAu/CZY were lower than those (42 and 88 kJ/mol) obtained over CZY for CO and toluene oxidation, respectively. On the basis of the characterization results and activity data, we conclude that the excellent catalytic performance of 4.7Au/CZY was associated with its higher oxygen adspecies concentration, better low-temperature reducibility, and stronger interaction between Au NPs and CZY nanorods as well as better Au NPs dispersion.