Microwave catalytic combustion of toluene by monolithic cobalt-based composite metal catalysts
A series of monolithic cobalt-based composite metal catalysts were prepared through impregnation method by combining cobalt(Co)with transitional metals copper(Cu),Manganese(Mn)and Cerium(Ce)as active components and using honeycomb cordierite as carrier.The catalytic activity of the catalysts was investigated using toluene as a kind of typical VOCs under microwave irradiation.The results showed that the catalytic activity of Co-based catalysts for toluene removal was in the order of CoCuCeOx＞CoCuOx＞CoCuMnCeOx＞CoCuMnOx when the inlet toluene concentration was 1000mg/m3with flow rate of 4L/min.The T50and T90of toluene achieved by CoCuCeOx catalyst was 220℃and 295℃,respectively.According to the characterizations analysis,CoOx,CuOx,and CuCo2O4spinel particles on the surface of the catalyst were formed into spherical structures with voids by the recombination of cobalt and copper oxides.However,the addition of manganese was not conducive to the formation of this spherical structure.The CuCo2O4 spinel was formed by the replacement of partial Co2+ in the structure of Co3O4 with Cu2+.The easily breakage of Co-O and Cu-O bonds in CuCo2O4 spinel promoted the adsorption and activation of gaseous oxygen,which was beneficial to the generation of surface reactive oxygen species that participated in the oxidation of toluene.The addition of Ce led to the conversion of Ce3+/Ce4+,which promoted the formation of abundant oxygen vacancies on the surface of CoCuCeOx catalyst and then acted as the active centers to promote the oxidative degradation of toluene.The coupling of cobalt,copper,and cerium changed the structure of the active components,which effectively improved the absorption performance and catalytic activity of the catalyst.It provided extensive application prospects in the technology of microwave catalytic combustion of VOCs.
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