Development of New High Porosity Diesel Particulate Filter for Integrated SCR Technology/Catalyst

摘要

Diesel engines are widely used to reduce CO_2 emission due to its higher thermal efficiency over gasoline engines. Considering long term CO_2 targets, as well as tighter gas emission, especially NO_x, diesel engines must become cleaner and more efficient. However, there is a tradeoff between CO_2 and NO_x and, naturally, engine developers choose lower CO_2 because NO_x can be reduced by a catalytic converter, such as a SCR catalyst. Lower CO_2 engine calibration, unfortunately, leads to lower exhaust gas temperatures, which delays the activation of the catalytic converter. In order to overcome both problems, higher engine out NO_x emission and lower exhaust gas temperatures, close-coupled a diesel particulate filter (DPF) system with integration of SCR catalyst technology is preferred. For SCR catalyst activity, it is known that the catalyst loading amount has an influence on NO_x performance, so a high SCR catalyst loading will be required. However, higher loading amount causes higher pressure drop for conventional DPF materials. Therefore, a high porosity DPF is requested for the integrated SCR concept. In this paper, the advanced high porosity DPF for an integrated SCR concept will be described. It contains a fundamental pore structure study to overcome the tradeoff between high pressure drop, high catalyst loadings, and sufficient soot filtration efficiency and experimental data using a gas burner, engine bench and vehicle; it also contains some durability test results.