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With the upcoming Euro 6c emission regulations, the performance of Diesel exhaust lines needs to be improved to meet NOX and soot emission targets. A promising exhaust line architecture to reach these requirements is the association of a Diesel Oxidation Catalyst (DOC), a Selective Catalytic Reduction coated on a particulate filter (SCR-F) and a Selective Catalytic Reduction (SCR) catalyst. To develop this system, the car manufacturers have to face several challenges. One of the first is the design of the exhaust line volumes, which has a strong impact on the light-off temperatures of the catalysts and so on system performance. Then, urea injection has to be optimized with an adapted control system to maximize NOx reduction while keeping low tailpipe ammonia emission. Moreover, performance degradation of catalysts due to harsh exhaust conditions during vehicle life time have to be detected by OBD system.

Adaptation of both oil based fuel and engine technologies are key enablers to reduce CO2 footprint as well as pollutant emissions. Recent work has demonstrated the potential of gasoline-like fuels to reduce NOX and particulate emissions when used in compression ignition engines. In addition, properties of naphtha produced directly from the atmospheric crude oil distillation process in a refinery offer significant CO2 benefits. When introducing such innovative fuel and engine, after-treatment investigations are mandatory to meet pollutant regulations. In that respect, this work focuses on investigating structure and properties of the particulates produced with naphtha fuel to validate Diesel Particulate Filter (DPF) design requirements. First, soot mass measurement techniques are detailed. Then, characterization of soot is performed through DPF pressure drop, soot oxidation rates with and without Fuel Borne Catalyst (FBC), composition & structure analysis.

The research on health effects of soot particles has demonstrated their toxic impact on humans, especially for the smallest ones that can pass through the lungs into the bloodstream and be transferred to other parts of the body. Since the Euro 5b regulation, the total particle number (PN) at the exhaust is limited, but the associated protocol developed by the Particle Measurement Program (PMP) group defined a counting efficiency at the 23 nm cut-off particle diameter to avoid measurement artefacts [1][2]. Recent studies have demonstrated that the last generation Euro 6 engines can emit as many particles in the range 10-23 nm as beyond 23 nm [3]. The SUREAL-23 project (Understanding, Measuring and Regulating Sub-23 nm Particle Emissions from Direct Injection Engines Including Real Driving Conditions), funded by Horizon 2020 EU-program, aims to develop sampling, conditioning and measuring instruments and associated methodologies to extend the existing protocol down to at least 10 nm.