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The trade-off between NOx and particulate matter (PM) has been a technological challenge with respect to diesel engine emissions. However, the practical use of diesel particulate filters (DPF) has made diesel emission control possible, in which NOx emissions are reduced through engine control and nearly all emitted PM is completely removed by DPF from diesel exhaust emissions. This has helped to contribute to laying the foundation for pursuing of the high theoretical thermal efficiency of diesel engines. However, it is also a fact that such emission controls have resulted in considerable impairments on the original and greatest advantages of diesel engines. This includes fuel penalties with accompanying increases in fuel consumption caused by pressure losses due to the attachment of the DPF itself and the accumulation of PM in the DPF, as well as fuel losses that occur when fuel is used to regenerate collected PM.

This paper describes the durability of the filtration layer integrated into Diesel Particulate Filters (DPFs) that we have developed to ensure low pressure loss and high filtration efficiency performances which also meet emission regulations. DPF samples were evaluated in regards to their performance deterioration which is brought about by ash loading and uncontrolled regeneration cycles, respectively. Ash was synthesized by using a diesel fuel/lubrication oil mixture and was trapped up to a level which corresponded to a 240,000km run, into the DPFs both with and without the filtration layer. Afterwards, aged-DPFs were measured with respect to their permeability, pressure loss, filtration efficiency, as well as soot oxidation speed using suitable analytical methods. Consequently, it has been confirmed that there was no noteworthy deterioration of the performances in the DPF with the filtration layer.