CuO/CeO₂ Prepared By Impregnation Method And Its Catalytic Activity For CO Oxidation

In this work, the effects of different parameters in the impregnation process on the physical-chemical properties and catalytic activity for CO oxidation of CuO/CeO2 catalysts were investigated.(1) The copper precursors with different thermal decomposition properties have a significant influence on the obtained copper species and their dispersity, which lead to the formation of different active sites and metal-support interaction. As a result, the catalysts from different copper presursors show different activity for CO oxidation. The metal-support interation will induce the generation of active CO adsorption sites (Cu+) and activate the lattice oxygen species at the interface between CuO and CeO2, which are benefical to the enhancement of catalytic activity. However, the residual anion (Cl- or SO42-) will inbihit the interation and play a negative role in the catalytic oxidation of CO. In addition, as the Cu species from different copper precursors exhibit different thermal stability, the effects of copper precursors are also related to the catalyst calcination temperature.(2) Different calnination atmospheres and modes affect the valence state and dispersity of the final Cu species when copper acetate is used as precursor. The ability of Cu species incorporating into CeO2 lattice is dependent on the valence of Cu species, in contrast with their dispersity. It is easier for the high valence of Cu species to enter into CeO2 lattice. In addition, the catalytic activity of CuO/CeO2 catalysts for CO oxidation has a less corelation with the CO adsorption ability, but is related closely to their low-temperature reducibility at about ambient temperature. CuO/CeO2 catalyst calcined under air stream at 500℃ shows better low-temperature reducibility at 30℃, so the best catalytic activity for CO oxidation can be obtained on it.(3) Comparied with the catalyst prepared by using water as solvent, the using of methanol can improve the activity of CuO/CeO2 catalyst, while the using of methanol-water mixed solution as solvent can improve the dispersion of CuO and facilitate the formation of Cu-O-Ce solid solution, which make the catalytic activit of CuO/CeO2 catalyst further increasing.(4) A modified CuO/CeO2 catalyst was prepared by surfactant-assisted impregnation method (surfactant is added into the impregnation solution). Compared with the conventional impregnation method, the midified impregnation can improve the dispersion of active copper species. As a consequence, the activity of the modified CuO/CeO2 catalyst is ehnhanced effectively.