Studies of the dispersion state of CuO on Ti02 and CeOr Ti02 and activity for NO+CO reaction

The activities of CuO supported on TiO 2 and ceria-modified TiO 2 in catalyzing the NO reduction by CO have been examined with a microreactor-GC NO+CO reaction system, and the catalysts characterized by physical adsorption, TPR, XRD and NO-TPD. The CuO/TiO 2 and CuO/CeO 2 -TiO 2 catalysts increase the NO reduction by CO, probably due to the surface dispersed CuO and fine CuO crystallites. Pore structure data show that the pore size distribution of TiO 2 is mainly as micro-pores and meso-pores, and the adsorption-desorption isotherm is the type IV of BDDT classification. TPR profiles indicate that Cu-Ti has four TPR peaks, a peak from highly dispersed CuO species, β peak from oxide clusters with a structure similar to CuO, y peak from CuO crystallites and δ peak from the interaction of CuO and TiO 2 , TiO 2 surface oxygen reduction. In addition, the phase change of TiO 2 doesn't show negative influence in catalytic activities. Among the tested catalysts, the catalyst with 12% CuO loading has the highest activity for NO+CO reaction, but at CuO loading of ≥3%, a crystallite of CuO has already been formed, which means that besides highly dispersed CuO, the CuO crystallite also plays an important role in NO+CO reaction, and the catalytic activities have a close relation with the CuO crystallite size and its micro structure data. NO-TPD profile also shows that the catalytic activities are closely related to NO dissociation - a rate-determining step for the NO+CO reaction, but are not affected by the amount of adsorbed NO.