Ito, Y., Shimoda, T., Aoki, T., Yuuki, K. et al., "Next Generation of Ceramic Wall Flow Gasoline Particulate Filter with Integrated Three Way Catalyst," SAE Technical Paper 2015-01-1073, 2015, doi:10.4271/2015-01-1073.
A Particle Number (PN) limit for Gasoline Direct Injection (GDI) vehicles was introduced in Europe from September 2014 (Euro 6b). In addition, further certification to Real Driving Emissions (RDE) is planned  , which requires low and stable emissions in a wide range of engine operation, which must be durable for at least 160,000 km. To achieve such stringent targets, a ceramic wall-flow Gasoline Particulate Filter (GPF) is one potential emission control device. This paper focuses on a catalyzed GPF, combining particle trapping and catalytic conversion into a single device. The main parameters to be considered when introducing this technology are filtration efficiency, pressure drop and catalytic conversion. This paper portrays a detailed study starting from the choice of material recipe, design optimization, engine bench evaluation, and final validation inside a standard vehicle from the market during an extensive field test up to 160,000 km on public roads. The collected results show that a high porosity catalyzed GPF has the potential to effectively and reliably reduce PN emissions over a wide range of engine operating points as shown by running several dynamic drive cycles and a field test. Even after collecting a certain amount of oil ash during the field test, and thus increasing exhaust aftertreatment system pressure drop, there is negligible impact on CO2 emissions and engine power output. Thus a ceramic wall-flow GPF is one of the potential solutions for future emission regulations beyond Euro 6.