Search Results

Diesel particulate filters (DPFs) are an essential aftertreatment component for reducing the PM emissions of diesel engine vehicles. Installation of a DPF can achieve high filtration efficiency, but PM filtration also causes a high pressure drop due to deep bed filtration. Consequently, periodic PM regeneration is necessary to keep a low pressure drop, but this causes significant deterioration in fuel efficiency. Improving the efficiency of PM regeneration and keeping the pressure drop low are major challenges faced by DPF manufacturers in meeting future CO2 emissions regulations. This paper presents a novel morphological catalyst layer for DPFs, which is located in the surface of the inlet DPF channels and has been formed into a highly porous and three-dimensional meshwork shape. These features enhanced not only the prevention of deep bed filtration to reduce the pressure drop, but also the soot-catalyst contact for a faster PM regeneration rate.

Recently, there has been increasing interest in catalysts with smaller volume for a Urea Selective Catalytic Reduction (SCR) system especially for use in heavy duty vehicles. In this study, several new concepts were developed in order to improve the deNOx performance of the SCR catalysts over a wide range of operating temperatures and this resulted in a compact SCR system. First, the urea decomposition process in diesel exhaust gas was elucidated. Several kinds of urea decomposition catalysts were investigated and the material which showed the best performance in NH3 (ammonia) formation was used to improve the low temperature performance of Cu-zeolite catalysts. Second, the method of reducing the amount of NH3 slip was investigated. It is well known that the amount of ammonia slip after the Urea-SCR system must be under 10 ppm and therefore materials with lower NH3 slip are preferred.