Influence of molar ratio and calcination temperature on the properties of TixSn1 -xO2supporting copper oxide for CO oxidation

TixSn1 O--x(2) mixed oxides were synthesized by the coprecipitation method. CuO/TixSn(1) O--x(2) catalysts were then prepared by wetness impregnation of the mixed oxides with Cu(NO3)(2). These catalysts were characterized using X-ray diffraction (XRD), laser Raman spectroscopy (LRS), H-2-temperature-programmed reduction (TPR), O-2-temperature-programmed desorption (TPD), X-ray photoelectron spectroscopy (XPS), and in situ Fourier transform infrared (FT-IR) techniques. The activities of the catalysts during CO oxidation were evaluated. The following observations were made: (1) CuO species can be highly dispersed on the TixSn1 O--x(2) supports, such that several surface Cu+ ions and oxygen vacancies are formed. (2) Among the prepared catalysts, the 5CuO/Ti0.75Sn0.25O2-600 degrees C catalyst exhibits the highest reducing property, which arises from the difference in electronegativity between Ti and Sn. (3) The CO species can adsorb on Cu+ and O-2 on the oxygen vacancy, which forms O-2(-) species. The in situ FT-IR results show that the Cu+-(CO)(2) species and O-2(-) adsorbed on the catalyst play a key role in CO oxidation. (4) The resistance of the catalysts to H2O is related to the Brunauer-Emmett-Teller (BET) surface area and the H2O adsorption on the catalyst surface. Furthermore, a possible reaction mechanism is tentatively proposed to understand this reaction. (C) 2015 Elsevier B.V. All rights reserved.