Effect of the nanoparticle size of supported copper-containing catalysts on their activity in the selective oxidation of CO in an excess of H2

Abstract

The catalytic properties of systems prepared by the supporting of CuO onto CeO2, ZrO2, and Zr0.5Ce0.5O2 with particle sizes of 15–25 nm (nitrate pyrolysis (p)) and 5–6 nm (microemulsion method (me)) in the reaction of CO oxidation in an excess of H2 were studied. In the latter case, the supports had an almost homogeneous surface and a small number of defects. The catalytic activity of (me) and (p) supports was low and almost the same, whereas the catalytic activity of CuO/(CeO2, ZrO2, and Zr0.5Ce0.5O2)(me) samples was lower than that of CuO/(CeO2 and ZrO2)(p). The maximum CO conversion (∼100% at 125°C) was observed on 5% CuO/CeO2 (p). The CO and CO2 adsorption species on (p) and (me) catalysts were studied by TPD. Differences in the compositions of copper-containing centers on the surfaces of (p) and (me) systems were found using TPR. The nature of the active centers of CO oxidation and the effect of support crystallite size on the catalytic activity were considered.