Xiaojiang Yao

Preparation, characterization, and catalytic performance of high efficient CeO 2 -MnO x -Al 2 O 3 catalysts for NO elimination

A series of CeO 2 -MnO x -Al 2 O 3 mixed oxide catalysts (Ce:Mn:Al mole ratio = 6:4: x , x = 0.25, 0.5, 1, 2) were prepared by a simple one-step inverse co-precipitation method to investigate the influence of the incorporation of Al 3+ into CeO 2 -MnO x mixed oxides. CeO 2 -MnO x , CeO 2 -Al 2 O 3 , and MnO x -Al 2 O 3 mixed oxides, and CeO 2 were prepared by the same method for comparison. The samples were characterized by XRD, Raman, N 2 physisorption, H 2 -TPR, XPS, and in situ DRIFTS. The catalytic reduction of NO by CO was chosen as a model reaction to evaluate the catalytic performance. The incorporation of a small amount of Al 3+ into CeO 2 -MnO x mixed oxides resulted in a decrease of crystallite size, with the increase of the BET specific surface area and pore volume, as well as the increase of Ce 3+ and Mn 4+ . The former benefits good contact between catalyst and reactants, and the latter promotes the adsorption of CO and the desorption, conversion and dissociation of adsorbed NO. All these enhanced the catalytic performance for the NO+CO model reaction. A reaction mechanism was proposed to explain the excellent catalytic performance of CeO 2 -MnO x -Al 2 O 3 catalysts for NO reduction by CO.

Effect of precursors on the structure and activity of CuO-CoOx/γ-Al2O3 catalysts for NO reduction by CO

Catalytic reduction of NO by CO was studied over a series of CuO-CoOx/γ-Al2O3 catalysts prepared by co-impregnation with different copper and cobalt precursors (acetate and nitrate) to evaluate the structure-activity relationship. The obtained samples were characterized in detail by means of XRD, LRS, XPS, H2-TPR and in situ FT-IR technologies. Results indicate that copper oxide is agglomerated while cobalt oxide is dispersed on γ-Al2O3 for the catalyst prepared from copper acetate and cobalt acetate precursors (CuACoA); CuxCo3-xO4 spinel is formed and agglomerated on the catalyst prepared from copper nitrate and cobalt nitrate precursors (CuNCoN); while both copper oxide and cobalt oxide could be homogeneously dispersed for the catalyst prepared from copper nitrate and cobalt acetate precursors (CuNCoA), which exhibits the best activity for NO reduction by CO. Probably the synergistic effect between dispersed copper oxide and cobalt oxide is propitious to the oxygen transfer, which could be the reason for its high activities. Finally, a possible reaction mechanism was tentatively proposed to explore the different catalytic performances in NO reduction by CO model reaction.