TPD and TPSR study of CO interaction with CuO–CeO 2 catalysts

Abstract

The interaction of CO and CO 2 with CuO–CeO 2 catalysts, prepared by a citrate-hydrothermal method, has been studied employing the techniques of temperature-programmed desorption (TPD) and temperature-programmed surface reaction (TPSR) of preadsorbed CO, as well as TPD of preadsorbed CO 2. The effect of copper content and activation temperature on the adsorptive behavior of the catalysts has been investigated. TPD studies of preadsorbed CO showed that a small fraction of CO is reversibly adsorbed, while most of it undergoes reaction with surface oxygen and desorbs as CO 2. Such profiles of CO 2 consist of a peak at 100–120 °C along with CO 2 desorption at high temperatures, which was significant for catalysts activated at 300 °C. TPSR of preadsorbed CO showed that reversibly adsorbed CO is highly reactive in the presence of gaseous oxygen. Catalytic sites, which form carbonates during interaction with CO, get eliminated with increase of catalyst activation temperature and do not contribute to the steady-state activity of the catalysts. The effect of CeO 2 appears to be mainly related to stabilization of highly dispersed copper oxide species and to creation of additional sites for CO adsorption and reaction, probably at the interface between the two oxides.