Three-way Catalyst Aging And Failure Mechanism

Gasoline vehicle exhaust after-treatment device durability has an important influence on reducing harmful substance discharge,this paper focuses on theresearch of three-way catalyst(TWC)aging and failure mechanism,from thermal aging and gasolinequality leads to failure of two aspects basedon the simulation test,andthe TWC conversion of comparative analysis.Using temperature rapid aging of the thermal aging simulation,aging temperature range from900? to 1350?,temperature gradient to 150?,aging simulation time for 10 and 20 hours.the TWC light-offtemperature,air fuel ratio window,oxygen storage capacity,and the catalyst surface area and microstructure were analyzed and compared.Aport fuel injection gasoline vehicle is selected for durability test.The effect of silicon in fuel on the performance of TWCis studied by monitoring the TWC light-off temperature,air fuel ratiowindow,oxygen storage capacity and the emissionsof the vehicle.The vehicle ran a durability test referred to the fifth phase of China light vehicle emission standards,and the TWC performance and vehicle emission performance were tested.The TWC thermal aging test results show that the effect of aging temperature on the performance of the TWC is more obvious than the aging time.The TWC aging temperature increases 150?and TWC light-off temperaturecharacteristicsand oxygen storage capacity will be greatly deteriorated.When the aging time is 10 hours,the aging temperature is increased from 1200? to 1350?,and the TWC oxygen storage capacity decreased 47 mg,and the HC light-offtemperature is increased by 10?.Under the aging temperature of 1200?,the aging time increased from 10 hours to 20 hours,but the oxygen storage capacity of TWC only decreased,and the light-off temperature of HC had no change.Through the analysis of the microstructure of TWC,the TWC surface coating gradually accumulated,and its specific surface area is decreased with the increase of aging temperature.The test result of the TWC performance shows that the effect of silicon on TWC is very obviousafter about 17000 km vehicle durabilitytest.The TWC inlet surfaceof substrate appeared serious choking,through the exhaust system back pressure testing.It isfound that the exhaust system back pressure is raisedabout 15 kPadue to the TWC channel chocking about more than 50%.According to the new Europe driving cycle(NEDC)emission test,some pollutant emission values were nearly five timeshigher thanthe fifth Chinese stage emission limit.The oxygen storage capacity decreased by 283 mg and the light-off temperature of HC raised 147? and the specific surface area decreased4.6m2/g,compared tothe previous test through the performance test of the failure of the TWC,The oxygen storage capacity is reduced by 48 mg compared to the standard fuel 160000 km vehicle durability test.