Study On The Catalytic Oxidation Of Diesel Soot By Potassium-modified Cerium-zirconium Solid Solution-based Catalysts

As an integral part of our lives,diesel engines have the advantages of high torque and good economic performance.However,diesel soot and particulate（PM）emissions are one of the main components of PM 2.5 in the air.Eliminating or reducing particulate matter from diesel exhaust is the key to current research.The catalytic combustion reaction of soot particles is a typical solid（soot particle）-solid（catalysts）-gas（O2）heterogeneous catalytic reaction,and the contact of soot particles with the catalyst is the key to the catalyst’s excellent activity.The three-dimensional ordered macroporous（3DOM）material can enhance the contact efficiency between the catalyst and the soot particles,make the soot particles contact with the active site inside the catalyst due to its ordered pore structure.In this thesis,a cerium-zirconium solid solution was selected as the carrier to support alkali metal K-doped Co3O4 to promote soot combustion.Co3O4 is supported on the catalyst surface as a highly active and stable active site.The doping of K species makes Co3O4 expose more Co³⁺active sites,and can improve the shortcomings of alkali metals on the surface.Potassium species on the catalyst surface can provide a new active site for catalyzing soot reactions,and as a molten salt,can enhance the catalyst’s contact with soot particles and adsorb more surface active oxygen species.The XRD,BET,SEM,TEM,H2-TPR,Soot-TPR and other characterization methods were used to characterize the catalysts and their physicochemical properties.Among them,the catalyst K0.5Co Ox/3DOM Ce0.8Zr0.2O2 has the highest catalytic oxidation activity,with T10（282℃）and T50（324℃）.In this thesis,three-dimensional ordered macroporous cerium-zirconium praseodymium solid solution catalysts were also prepared.After screening the most suitable ratios,they were doped with K in different contents.During the doping process,a large number of alkali metal species were not found on the catalyst surface.With the increase of the K doping amount,the catalyst’s ability to oxidize soot first increased,and then decreased,finally remained unchanged,reaching the best result when the doping amount was 0.3（T50 is 350.8℃）.