Four-way Catalytic Regeneration Of Diesel Particulate Filter

With the rapid development of the automotive industry, pollutants of vehicle emissions have caused pollution to the environment and harm to the health of-people at the same time. The pollution of car emission has attracted the attention of countries. The countries have launched a variety of regulations to control the pollution of vehicle emissions. Gasoline engine pollution of emissions has been controlled well through the internal purification techniques and the three-way catalytic converter, but there are compromise relationship (Trade-off) with the diesel engine when reducing the emissions of NOx and PM. What’s worse, NOx and PM are the main pollutants of the emission of diesel engine. So to reduce the emission of diesel engine is a major problem. But the DPF which is the most effective technique for the purification of PM is not widely used for its regeneration technology. Basing on this situation, four-way catalytic regeneration technology come up with, which aims to achieve the regeneration of the DPF and to reduce the emission of other pollutants, mainly the NOx. Finally, that is to meet the requirements of increasingly stringent emissions regulations.Through analysis of the characteristics of various types of catalysts, it can be seen that the perovskite-type catalysts have the advantage of anti-sulfur ability and other advantages. There is a large amount of rare earth elements in our country and low price and good economic returns when comparing to the less noble metal catalysts. Basing on the features and the research of perovskite-type catalyst La0.9K0.1FeO3, La0.9K0.1FeO3is selected as the catalyst which to achieve four-way catalyst regeneration of DPF. Then there are comparisons that the advantages and disadvantages of different regeneration ways of DPF and analysis on the feasibility of the four-way catalytic regeneration of DPF.The activity of catalyst is directly affected by the preparation methods. By analyzing the characteristics of different catalyst preparation methods and the research condition of sol-gel method used in the field of catalyst’preparation, sol-gel method is chosen as the method to prepare the catalyst La0.9K0.1FeO3. The article also studied how did the PH value of the precursor solution and the roasting temperature impact the catalyst grain size and specific surface area. Finally through experiments, the precursor’s PH value of La0.9K0.1FeO3is determined, that is5to6, and the roasting temperature of La0.9K0.1FeO3is also determined, that is800℃. The DPF four-way catalytic regeneration dyno test shows that when the engine exhaust temperature is low, the DPF regeneration and NOx purification basically are not be achieved. But when exhaust temperature is high, the DPF regeneration and NOx purification begin to improve. For example, on the fifth operating point, the DPF regeneration rate is15%and the purifying rate of NOx is12.2%. When the engine exhaust temperature is low, the purifying rate of HC and CO is not obvious, but when the exhaust temperature is high, the purifying rate of HC and CO is improved.Activity of catalyst is affected by the temperature. When the engine is on small load and middle load, the exhaust temperature of engine is low. So the DPF regeneration and NOx purification almost does not achieve. So the electrical heating is used to optimize the DPF four-way catalytic regeneration, in order to expand its applicable range of operating conditions. The experiment results show:Some conditions which the engine exhaust temperature is low, after heating, DPF regeneration can be achieved which used to not. After heating, NOx also can be reduced which used to not. What’s more, as the heating temperature increase, the DPF regeneration rate increase, the NOx purification also has been improved in a certain temperature range.