The Research On Comprehensive Control Technology Of PM And NO_x From Diesel Engine

Gasoline engine and diesel engine are two primary kinds of engines used in vehicles. The diesel engine is widely used than before and has gradually become the first choice for automobiles, because of its higher fuel economy and lower HC and CO emissions. However, the high PM and NO_x emissions slow down the development of diesel engines. Although there is a long time in the research on respective control techniques of PM or NO_x emissions from diesel engine, the research on comprehensive control techniques of PM and NO_x emissions is a new issue.PM and NO_x generated by the different mechanisms, to achieving the purpose of reduce PM and NO_x at the same time, the simple use of the control techniques in engine technology is not enough, we also need after-treatment technologies. Through analyzing PM and NO_x control methods separately, this paper presents the technical route of diesel PM and NO_x combined control, and particularizes programs which has now been identified or are still in the research stage, in order to prove that the t technical route proposed reasonable. Then by compare among these technical routes and programs, the author believes that in the oxidation environment, the use of catalytic methods removing both NO_x and PM is a better method.Among numerous of catalyst that used to removing NO_x and PM together, Perovskite Composite Oxide is considered to be one of the best catalysts for the moment. On the base of other researches, We direct against La_0.9K_0.1CoO₃ in the calcium titanium ore type compound oxide, utilize Solid state reaction method and Sol-gel method at 800℃, 950℃, 1050℃, have prepared out six groups of La_0.9K_0.1CoO₃.Through physical detection means, we think the higher the temperature is, the better the physical performance of La_0.9K_0.1CoO₃ is as the catalyst;At the same temperature, the physical performance of La_0.9K_0.1CoO₃ as the catalyst which made through Sol-gel method is better.Catalyst for the use of the subminiature catalytic reactor the multi-group La_0.9K_0.1CoO₃ chemical catalytic performance tests conducted, through experiments, it proved that La_0.9K_0.1CoO₃ can also remove PM and NO_x in the tail gas;the higher the temperature is, the better the catalytic functions of Perovskite La_0.9K_0.1CoO₃ prepared by Sol-gel method. On this basis, in order to further reduce the initial reaction temperature in the PM and NO_x reaction, the author puts forwards on the basis of other people's theories the combined use of nobel metals Pt and La_0.9K_0.1CoO₃ as the catalyst in the PM and NO_x reaction. Despite the unsatisfactory results of experiments, these provide a reference for future improvements.To test the actual catalysis effect of catalyst, it will be coated in Diesel honeycomb ceramics carrier as after-treatment of the diesel in diesel test bench for practical experiments, the conclusion: the catalyst in certain temperature can not only to reduce both PM and NO_x in diesel tail gas, but also can reduce HC and CO emissions, But for PM and NO_x ,the conversion efficiency is relatively low, in the best of cases only 15%²0%;compared with other technologies, there are some distance from this technology to practical applications.