Study On Catalytic Performance Of Monolithic Three-dimensional Ordered Macroporous Manganese-based Perovskite Catalyst For Toluene Combustion

In recent years,the economy of my country has developed rapidly,the level of industrialization has been continuously improved,and Residents’living standards has also been greatly improved,and the resulting air pollution problem has become increasingly serious.The exhaust emissions of the petrochemical industry and the emergence of automobile exhaust,chemical pollution and building decoration and other problems pollute the environment.Among them,the emissions of volatile organic compounds（VOCs）are relatively large,which has brought many adverse effects on human life.As a high-efficiency VOCs treatment technology with low energy consumption and no secondary pollution,the core of catalytic combustion technology is to prepare high-efficiency catalysts to improve catalytic performance.Among the current ABO₃perovskite catalysts with more lattice defects and higher oxygen mobility,the manganese-based perovskite catalyst,as a non-precious metal material,has high cost performance,good catalytic activity,and strong stability.And other advantages perform well in the treatment of catalytic combustion VOCs.The three-dimensional ordered macroporous（3DOM）material can make up for the disadvantage of the small specific surface area of the perovskite catalyst due to its single pore size and the orderly arrangement of the pore structure in a three-dimensional space.In addition,the monolithic catalyst with honeycomb ceramic cordierite as the carrier has the advantages of reduced pressure,regular arrangement of pores,and improved utilization efficiency of the catalyst,which can be explored by researchers and can innovate a series of future applications that can be applied to industrial production.This paper would use PMMA hard template-excess impregnation method to prepare a series of monolithic 3DOM AMn O₃（A=Ce,La,Ni）to explore the effect of different A-site elements on the three-dimensional ordered macroporous structure and catalytic combustion performance.After the optimal A-site element,the optimal preparation conditions of the catalyst were investigated by changing the Ce/Sr doping ratio,the calcination temperature of the catalyst,and different loadings during the preparation process.After characterization and analysis,the optimal preparation conditions of the macroporous structure and the catalyst with the best catalytic effect were screened out.On this basis,the influence of the catalyst on the catalytic combustion of toluene was discussed.The results of the experiment are as follows:（1）The catalysts corresponding to different A-site elements have a greater impact on the performance of catalytic combustion of toluene.The experiment proves that the catalytic activity of the monolithic 3DOM Ce Mn O₃is the best,when the intake concentration of toluene is 500±50 mg·m^-3,the space velocity is 6000 h^-1,T₅₀and T₉₀are 150℃and 216℃respectively.（2）Under the conditions of loading of 20%and calcination temperature of 600℃,when x for the monolithic 3DOM Ce_1-xSr_xMn O₃catalyst is 0.2,the three-dimensional order of the monolithic 3DOM Ce_0.8Sr_0.2Mn O₃catalyst is large.The pore structure is relatively more complete,the specific surface area(35.2 m²·g^-1)is the largest,which is conducive to the exchange of substances,and the higher lattice oxygen concentration is convenient for the subsequent catalytic combustion reaction of toluene.When the toluene intake concentration is 500±50 mg·m^-3and the volumetric space velocity is 6000 h^-1,the corresponding T₅₀and T₉₀of the monolithic 3DOM Ce_0.8Sr_0.2Mn O₃catalyst are136°C and 195°C.（3）The catalytic combustion process of the monolithic 3DOM Ce_0.8Sr_0.2Mn O₃catalyst for toluene belongs to the category of first-order kinetics.The catalyst has an initial concentration of 500 mg·m^-3and a space velocity of 6000 h^-1for the removal of toluene.Best,after 40 hours of stability test analysis,the toluene removal rate is still maintained at about 80%,and the stability is good.It can be seen that the monolithic 3DOM Ce_0.8Sr_0.2Mn O₃catalyst prepared in this experiment meets general industrial needs.