It is foreseen that advanced diesel engine combustion technologies such as the Homogeneous Charge Compression Ignition (HCCI) and Highly Premixed Combustion (HPC) will be employed by the diesel engine powered vehicles in the near future. These technologies are often referred to as Low Temperature Combustion (LTC) technologies. The engine operation under LTC conditions results in lower NO_x and higher HC and CO emissions than the conventional engine operation. The low NO_x exhaust concentration brings difficulties to the application of today's particle emission control systems (combinations of Diesel Oxidation Catalysts, DOCs and Catalyzed DPFs, CDPFs) which are mostly based on the NO_2-assisted soot oxidation for the regeneration of the filter. The low-NO_x concentration will inevitably lead to more frequent active regenerations (T>600°C) and as such to higher fuel consumption associated with the filter regeneration. The latter is in the opposite direction of the increasing importance of lowering the CO_2 vehicle emissions. The increased CO and HC concentration in the LTC exhaust calls for the incorporation of advanced oxidation catalysts in the exhaust aftertreatment system. The necessity of advanced catalyzed DPFs able to operate efficiently in that kind of exhaust environments is obvious. In the present paper the research and development efforts for the realization of a Multi-Functional catalyst Reactor (MFR) are presented. This work is based on recent advances in catalytic nano-structured materials synthesis and coating techniques. Different catalytic functionalities have been carefully distributed in the filter's substrate microstructure for maximizing the direct and indirect (NO_2-assisted) soot oxidation rate, the HC and CO conversion efficiency as well as the filtration efficiency. Moreover, a novel filter design has been applied to enable internal heat recovery capability by the implementation of heat exchange between the outlet and the inlet to the filter flow paths. The performance of the developed MFR has been evaluated at an engine test bench and the results are presented in this paper.
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