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

Diesel engines are widely used to reduce CO₂ emission due to its higher thermal efficiency over gasoline engines. Considering long term CO₂ targets, as well as tighter gas emission, especially NOx, diesel engines must become cleaner and more efficient. However, there is a tradeoff between CO₂ and NOx and, naturally, engine developers choose lower CO₂ because NOx can be reduced by a catalytic converter, such as a SCR catalyst. Lower CO₂ 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 NOx 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 NOx 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.