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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.

A one-dimensional (1-D) micro-kinetic reaction model with considering mass transport inside porous washcoat was developed to promote an effective development of multi-functional catalysts. The validation of this model has been done successfully through the comparison with a set of basic experiments. A numerical simulation study was conducted for the various catalyst configurations of three-way catalysts under Federal Test Procedure (FTP75) condition. It was found that a double layer type had a significant advantage in the total mass emissions, especially in NOx emissions. The reaction mechanisms in these catalysts were numerically clarified from the view point of detailed reaction dynamics. We concluded that the utilization of the numerical simulation with the detailed chemistry was effective for the optimization of catalyst design.

The new concept catalyst for diesel engine has been developed. When the exhaust temperature is low, SOF and HC are temporarily adsorbed by the adsorbent within the catalyst and are oxidized as the temperature rise. This is a different that the low-temperature oxidation activity is appeared by the noble metal loading of the catalyst. The process of this development have manifested as follows. 1. The coating material is important factor to govern the oxidation activity. 2. SOF is reduced by the coating material in low temperature less than 200 3. The coating material, which has low SO2 adsorbing rate suppress the sulfate formation at high temperature. 4. To reduce NOx in the diesel engine exhaust gas is possibility by utilizing adsorptive characteristics of the catalyst.

In developing an oxidation catalyst for reducing diesel particulates, it is necessary to balance two conflicting characteristics. One is high oxidizing activity so that the catalyst can reduce the Soluble Organic Fraction (SOF) efficiency even at low exhaust temperatures. The other is the suppression of sulphate formation at high exhaust temperatures. First it was studied that active metals and coating materials are given effects on the reduction of SOF, the formulation of sulphate and durability, by using catalysts equivalent in composition to the oxidation catalyst for gasoline-engines. Based on these findings, a two-stage catalyst wasdeveloped. It satisfies the two characteristics at a comparatively high levelby slecting materials and optimizing the catalyst composition.