CO oxidation on ceria- and manganese oxide-supported gold catalysts

Abstract

A comparative study on ceria- and manganese oxide-supported gold catalysts for the oxidation of carbon monoxide at low temperature was investigated. Nanostructured gold catalysts supported on CeO 2 and MnO 2 were prepared by deposition–precipitation method. The influence of calcination temperatures before (200 °C and 400 °C) and after (120 °C and 180 °C) gold loading on CeO 2 and the effect of crystalline nature on the catalytic activity of Au/MnO 2 were also studied. The structure, morphology, and electronic properties of the catalysts were analyzed by X-ray diffraction, transmission electron microscopy, and X-ray photoelectron spectroscopy. CeO 2 prepared in this study was in nanosize range, which could confine the Au particles in nanosize range. Fine dispersion of gold nanoparticles on CeO 2 and MnO 2 was confirmed. Existence of Au 0 and Au 3+ states were noticed on Au/CeO 2 catalysts, whereas only metallic gold was detected on Au/MnO 2. The redox efficiency of CeO 2 and MnO 2 is responsible for high CO conversion at room temperature. Au/CeO 2 (support was calcined at 400 °C and Au catalyst was calcined at 180 °C) demonstrates higher catalytic activity for CO oxidation than Au/MnO 2. The co-existence of metallic and oxidized gold species on Au/CeO 2 seems to be the main reason for the higher activity of Au/CeO 2 with respect to Au/MnO 2.