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The heavy duty (HD) Eu VII regulations, going into effect starting 2027, has aggressive particle number (PN) emissions limits under extended operating conditions compared to existing Eu VI framework. In addition to the proposed hot-start PN limit of 2.0E+11 #/kWh, which is a >65% reduction vs. Eu VI E, the particle size cut-off is being extended from 23nm+ to 10nm+ while also including nearly all field operating conditions such as regeneration events, wider ambient boundaries etc. The tighter limits coupled with a work-based window approach to evaluate emissions is driving the need for the next generation of ultra-high filtration efficiency (FE), diesel particulate filter (DPF) technologies. The current study evaluates the FE performance of different DPF solutions under development, over a range of challenging on-road conditions characterized by frequent high temperature events which are not actively triggered.

China 6 (CN6) emission legislation for light duty vehicles was published in 2016, which introduced real driving emissions (RDE) requirements for new type-approval content. Nitrogen oxides (NOx) and particle number (PN) of RDE test are required to be monitored and reported from July 2020 in CN6a phase, fulfilled from July 2023 in CN6b phase. To meet the PN limitation of CN6 RDE, the optimized engine combustion and advanced emission control system like gasoline particle filter (GPF) are encouraged. Compared to traditional vehicle platform emission compliance which could be done in lab, much more vehicle development and validation efforts are expected on the open road for RDE compliance. High cost and complexity are expected to conduct a complete validation test matrix covering all the RDE critical boundary conditions on the open road.

With the introduction of EU6d and CN6 all vehicles with gasoline direct injection and many with port fuel injection engine will be equipped with a gasoline particulate filter (GPF). A range of first generation filter technologies has been introduced successfully, helping to significantly reduce the tailpipe particulate number emissions. The continued focus on particulate emissions and the increasing understanding of their impact on human health, combined with the advanced emission regulations under RDE conditions results in the desire for filters with even higher filtration efficiency, especially in the totally fresh state. At the same time, to balance with the requirements on power and CO2, limitations exist with respect to the tolerable pressure drop of filters. In this paper we will report on a new generation of gasoline particulate filters for uncatalyzed applications.