Study On The Synthesis Of La?Pt/Pd?_xMn_1-xO₃ Catalysts And The Catalytic Properties Toward Soot Of Gasoline Exhaust

Recently,Particulate Filters have been applied a lot in the area of automotive exhaust emissions removal while the process of regeneration of the Particulate Filter became a key issue.The current solution of this problem is the application of the catalysts to oxidize the particulates,which mainly consisted of soot,especially in the temperature level up to 500°C.Noble metals and perovskites both played an important role in the catalytic oxidation.In our research,a series of La?Pt/Pd?_xMn_1-xO₃ catalysts composed by noble metals and perovskites have been synthesized using a modified sol-gel method.Followed by the characterization of N₂ adsorption-desorption isotherms,XRD,SEM,TEM,XPS and H₂-TPR to study the physic-chemical properties of the catalysts.The catalytic properties towards soot combustion were researched by a fixed-bed temperature-programmed oxidation?TPO?system.It should be pointed out that the TPO process was carried out in an atmosphere to simulate the practical applied situation of gasoline engine,which is a new area in the domestic academic research.The modified sol-gel method utilized the glucose as a replacement of citric acid.Meanwhile,the application of rotary evaporator has improved the synthesis process compared with the conventional ageing process and shortened the synthesis period.XRD results showed that these La?Pt/Pd?_xMn_1-xO₃ samples possesses a pure ABO₃ perovskite structure when x?0.2,which means noble metal constituents have went into the perovskite structure.Along with the increase of the portion of noble metal,it tended to separate out from the perovskite space lattice and form to another phase with a smaller size.The samples showed a heterogeneous structure.The SEM and TEM results revealed that La?Pt/Pd?_xMn_1-xO₃ sample has a good crystalline form and a size of about100 nm.These samples have a large surface area about 16 m²/g and lots of mesoporous structures.Besides,H₂-TPR results showed that the La?Pt/Pd?_xMn_1-xO₃ had a fabulous redox ability.The ignite temperature of the samples have been lowered from 147?to 144??x=0.1?,145??x=0.2?and131??x=0.3?,respectively,show a better catalytic activity in lower temperature.Besides,the concentrations of CO₂ at T_m were enhanced in a different range,which means the catalytic effectiveness were better than before.This research results expanded the research area of the noble metal replaced perovskite and its application in the catalytic oxidation toward soot combustion especially in the gasoline exhaust atmosphere.These results will be an important theoretic supports for the potential application of the novel catalysts in the area of gasoline automobiles and engines.