Structural Analysis Of 3DOM-m Ti_xSi_1-xO₂-supportted Manganese-based Catalysts And Analysis Of Their Catalytic Performances For Soot Combustion

The soot particles emitted from diesel engines have caused great harm to human health and the environment.The aftertreatment technology is one of the most effective methods to reduce the emission of soot from diesel vehicles.However,an important factor for restricting development of the aftertreatment technology is the development of high active catalysts.Manganese-based catalysts are widely used in the catalytic combustion of soot particles due to their variable valence state and environmental friendliness.The catalytic soot combustion is a typical heterogeneous catalytic reaction,which takes place at the three-phase boundary among gas-solid-solid.In addition to the intrinsic activity of the catalyst,he effective contact between catalysts and soot also affects the catalytic performance.Three-dimensionally ordered macroporous-mesoporous material is one kind of porous materials,which composed by macropores and mesopores.At the same time,they have a uniform and orderly pore,and high pore volume.The unique macroporous structure and high pore volume make up for the shortcomings of previous catalysts that make it difficult for macromolecules to enter the pores and mesopores can activate small molecules.Therefore,three-dimensionally ordered macro-mesoporous materials have been greatly developed in the catalytic combustion of soot particles.（1）First,the macroporous template was synthesized by K₂S₂O₈ and refined MMA.Then,3DOM-m Ti_xSi_1-xO₂ with different ratio of titanium to silicon was prepared by impregnating the prepared macroporous template into a mixed solution which include different ratio of tetrabutyl titanate to TEOS and PEO-PPO-PEO.When the Ti/Si is 0.7:0.3,the carrier has a mac-mesoporous structure and the activity is optimal.（2）The 3DOM-m Ti_0.7Si_0.3O₂ supported nanoparticles which compose by alkali and rare earth metals（Li,Na,K,Rb,Cs,Mg,Ca,Ba,Sr）mixed with manganese were prepared by simple impregnation method and then the YMnOx/3DOM-m Ti_0.7Si_0.3O₂catalysts were prepared（Y is alkali,alkaline earth metal）.Different composited metal oxide catalysts exhibit different redox performance.3DOM-m Ti_0.7Si_0.3O₂-supported composited metal oxides catalysts show different catalytic activities for diesel soot combustion.The best catalytic activities of as-prepared catalyst is CsMnO_x/3DOM-m Ti_0.7Si_0.3O₂.However,the price of cesium is much higher than that of potassium in practical application.Thus,by comprehensive consideration,potassium is more suitable than cesium for practical application.（3）Potassium-manganese composite metal oxides with different loading and different calcination temperatures were perpared by simple impregnation method.When the load amount is 40%and calcination temperature is 450 ^oC,the catalysts greatly reduce the combustion temperature of soot.The catalyst was tested with soot for five cycles and the results show that the catalysts have good thermal.At the same time,the catalysts were tested for activity under different concentrations of NO and SO₂.The result indicates that when the concentration of NO increases,the activity of the catalyst will increase.However,when the concentration of SO₂ increases,the activity of the catalyst will decrease.