Study On Catalytic Performance Of Copper-manganese-cerium Complex Oxides Catalyst For Ventilation Air Methane Combustion

At present,the most effective use of ventilation air methane is to convert it by catalytic combustion.Transition metal oxides,such as copper and manganese,are promising catalysts for catalytic combustion due to their low cost and good comprehensive performance.However,they have the problems of high ignition temperature and complete combustion temperature for catalytic effect.In this paper,binary or ternary catalysts were prepared by ceria,copper and manganese oxides,and their catalytic performance for ventilation air methane combustion was studied.Firstly,the co precipitation method,sol-gel method and hydrothermal synthesis method were used as the preparation methods.Cu-Mn composite oxide catalyst with Cu/Mn molar ratio of 1:1 was prepared at the temperature of 500,650 and 800 degrees respectively.The fixed-bed reactor was used to evaluate the Cu-Mn composite oxide catalyst catalytic ventilation air methane combustion activity,and then the preparation method and roasting temperature of the catalyst were screened.The results showed that the catalyst prepared by the hydrothermal synthesis method at the calcination temperature of 500? has good catalytic activity.Secondly,the binary and ternary composite oxide catalysts with different molar ratios of Cu/Mn,Cu/Ce,Mn/Ce,and Cu/Mn/Ce were prepared by hydrothermal synthesis at a calcination temperature of 500?.The microstructure and properties of the catalysts were characterized by scanning electron microscopy(SEM),X-ray photoelectron spectroscopy(XPS),nitrogen adsorption desorption(N₂-BET),temperature programmed reduction(H₂-TPR)and X-ray diffraction(XRD)The physical and chemical properties of the catalysts were characterized systematically.Combined with the experimental results of catalytic combustion activity evaluation of ventilation air methane,the metal components and their molar ratios of the composite oxide catalysts suitable for catalytic combustion of ventilation air methane have been determined.The results showed that the binary catalyst with Cu/Mn molar ratio of 1:1,Mn/Ce molar ratio of 7:3 and Cu/Ce molar ratio of 7:3 had higher activity,and the ternary catalyst with Cu/Mn/Ce molar ratio of 1:3:1 and 3:1:1 had higher activity than the binary catalyst.This is because in the ternary catalyst,more Cu and Mn ions are formed.Due to the excellent oxygen supply ability of CeO₂ Fluorite Crystal,some of these ions will combine with oxygen to form highly active oxides,and some of them will enter the CeO₂ lattice to form solid solutions.Therefore,the active phase will be distributed on the surface of the catalyst to promote the reaction.In addition,compared with Cu-Mn binary catalyst,Cu-Mn-Ce ternary catalyst shows a low temperature reduction peak in hydrogen programmed reduction characterization,and the binding energy of O1s in XPS characterization is higher.It is concluded that the defects in cerium based solid solution have better oxygen capacity.Therefore,Cu-Mn-Ce ternary catalyst can obtain higher activity.