Research Of The Deactivation On Advanced Exhaust Emission Control System

Now the pollution become more serious, the exhaust of the car is the main source. In order to control the exhaust, some advanced technologies are adopted. Catalyst is important to control automotive exhaust, its efficiency to transform HC, NOx and CO is more than 90%. Because the condition is serious, the catalyst may be malfunction. In this condition, we analyze the deactivation by use of the physical and chemic techniques.The creation and the working principium of the catalyst is discussed firstly. We study the relation between the BET and the efficiency. Then, the reasons of the deactivation are introduced. Generally thermal aged and chemical poisoning can lead to the deactivation. Catalyst is worked in the high temperature, a phase transformation of the washcoat is often observed. Sulphur, phosphorus, zinc from various sources (fuel, air and lubrication oil) may result in a slow build-up of poisons on the catalyst surface, which yields a surface phase which is virtually inactive for the desired reactions.Then, we research the physical and chemic techniques in detail, and analyze the deactivation of the catalyst in use of our test system at present. We test the exhaust, BET and mental elements, and analyze their relations.To analyze the deactivation of the catalyst, we choose a seriously deactivated catalyst. The techniques of BET analysis, XRD analysis and XRF analysis are adopted, we test the total surface area, the Al₂O₃'s state and the weight of the poison elements and analyze their relation. The degree of the deactivation is determined.Than the fresh catalyst, in the deactivation noble metal become big, and the total surface area become small. The component concentrations of the poison elements, as are more. In our country, the reason of the deactivation is mainly the poison deactivation. The poison and thermal conditions are very different at different locations. The thermal deactivation mainly occurs in the center, and the composition of the poison declines strongly with the distance from the front. In the last, the research system of the catalyst is built.