Study on the Effects of Different Catalyst Loadings on Diesel Engine Emission Characteristics with DOC Coupled SCR

DOC coupled with SCR is an important technical route for reducing gaseous pollutant emissions from diesel agricultural engines. Based on engine bench tests, this paper uses a diesel engine as a prototype to experimentally study the impact of different catalyst loadings on the emission characteristics of diesel engines when coupled with DOC and SCR. The results show that the higher the loading of the DOC catalyst, the greater the exhaust back pressure loss, with the maximum pressure difference reaching 4.9 kPa. The temperature difference before and after the DOC has a smaller impact with varying catalyst loadings. The higher the loading of the DOC catalyst, the stronger the catalytic activity for CO and THC. At medium and low loads, the impact of catalyst loading is more significant, while at high loads, it has a smaller impact. The higher the loading of the DOC catalyst, the stronger the oxidation ability for NO. Under external characteristic conditions, due to the higher engine exhaust temperature, the maximum NO2 generation rate after the DOC is achieved, and the NO2 generation after the DOC can be increased by more than 100%.