Study On Co-based Perovskite Composite Oxide Catalysts For Deoxidization In Coal Bed Methane

Coal bed methane (CBM), also known as coal mine methane and coal seam gas, is a kind of good energy resource whose major component is CH4. It is inevitably that oxygen may mix into CBM when it is exploited. There is a risk of explosion when methane and oxygen mixed together, so oxygen must be removed before using the CBM. In this thesis, we have used the method of catalytic deoxidization to remove oxygen in the CBM by the catalytic combustion of methane. In the process of CBM deoxidization, some side reactions may take place, such as methane partial oxidation, steam reforming and so on. So it is very important to design and prepare an appropriate catalyst.In this thesis, the catalytic performances of the Pd noble metal, Cu-Ce mixed oxide, Co and Mn-based perovskite and hexaaluminate composite oxides were investigated for a deoxidization in CBM. The results show that the methane partial oxidation occurs more easily on Pd noble metal catalyst and LaMnO3 perovskite composite oxide catalyst, and using LaCoO3 perovskite catalyst the deep oxidation of methane occurs only. Based on the advantages of the stability and activity of LaCoO3 catalyst, it was studied as the model catalyst. We wanted to control the methane conversion in the methane catalytic combustion by designing catalyst and catalyst bed, and at last we found it is difficult to control the strong exothermic reaction.The influences of doping with other elements on the physicochemical properties and catalytic properties of LaCoO3 were studied by means of N2 adsorption-desorption, XRD, FT-IR, H2-TPR, CH4-TPR-MS, and so on. The results show that, for the samples of substituting Bi for Co in the B sites of LaCoO3, the activity of LaCoO3 perovskite catalyst decreased with the increase of Bi content. When the LaCoO3 perovskite substituted rare earth metal (Pr or Er) for La in the A sites, and its catalytic activity was improved largely, in which the proper content of doped Pr or Er need be controlled. The proper doping content of Pr is 10% and Er is 20%. Among the catalysts studied, the Lao.gEr0.2Co03 catalyst behaves the most catalytic activity for a deoxidization in CBM.The influences of the calcination temperature, precipitant, preparation method and calcination time on the properties of La0.8Er0.2CoO3 catalyst were investigated. The results show that, the La0.8Er0.2CoO3 catalyst prepared by coprecipitation method with NaOH as precipitant and calcined at 750℃for 2 h, exhibits the excellent catalytic activity and thermostability for a deoxidization in CBM.