Preparation And Catalytic Decomposition Of Cobalt Salt Catalysts N ₂ O

With the development of chemical industry, the emission of N2O gas from industryprocesses gives an increasing trend. N2O with310of GWP relative to CO2is one of thesix greenhouse gases limited by Kyoto Protocol. Therefore, the destruction of N2O beforeemission is an urgent and meaningful work.In this thesis, M-Co (M=Cu, Mn) mixed oxides with spinel structure were preparedby co-precipitation method, and their catalytic activity for N2O decomposition underoxygen condition was investigated. The effect of catalyst preparation parameters, such ascomposite oxide composition, calcinations temperature, promoter species, K precursors,and K loadings on the activity was discussed. In addition, the catalysts of Au/Co3O4wereprepared by deposition-precipitation method using HAuCl4solution with different pHvalues pre-adjusted, the Au/ZnCo2O4catalyst was prepared using optimal parameters, andtested in N2O decomposition. AES, XRD, BET, H2-TPR, XPS and SEM techniques areused to characterize these catalysts.The conclusions have been drawn as follows:(1) The Cu0.8Co0.2Co2O4calcined at400C and Mn0.4Co0.6Co2O4calcined at500Cexhibited a high activity for N2O decomposition in the corresponding catalyst series. Thecatalytic activity of K-promoted CuCo, MnCo mixed oxides for N2O decomposition ismuch higher than that of bare oxides. The characterization data suggested the M-O bondwas weakened, thereby the oxygen desorption became more facile during the reaction.(2) Potassium precursors produced an obvious effect on K-modified catalysts activity.It is found that K-modified catalysts prepared by the impregnation of K2CO3solutiondisplayed high activity, stability and water resistance.(3) The0.29%Au/Co3O4catalyst prepared by HAuCl4solution with pH value of9exhibited a high catalytic activity. It is found that ZnCo2O4was more active than Co3O4,whereas the0.31%Au/ZnCo2O4exhibited a lower activity than0.29%Au/Co3O4. Thecharacterization data indicated that a synergistic effect between gold and cobalt species inAu/Co3O4resulted in the enhanced performance, but no such synergistic effect existed in Au/ZnCo2O4.