Coated Gasoline Particulate Filter Technology Development to Meet China6 PN Regulation

With the introduction of stringent particulate number (PN) limit and real driving emission (RDE) requirements, gasoline particulate filters (GPFs) are widely adopted in Europe and China. GPF can be wash-coated with different level of three-way catalyst (TWC) coating. Some applications use heavy coating (>100g/L), and some don’t use at all. Pressure drop (DP) and PN filtration efficiency (FE) are the top two design criteria for OEMs. It is important to understand how various of coating technologies work with GPF technologies for optimized FE/DP performance. To study filter and coating interaction, a big matrix of coated GPFs are prepared and tested for lab DP and vehicle PN based FE. The matrix includes a wide range of wash coating loadings (WCLs), coating technologies that enable more coating inside GPF filtration walls (in-wall coating) or more on top of walls (on-wall coating), and GPF technologies with high and low mean pore size (MPS). Scanning electron microscope (SEM) is used to analyze microstructure of coated filter walls, and coating distribution for better understanding filter performance data. In general, DP and FE of coated filters increase with WCL. Filters with lower MPS have higher DP and FE. Coating technology with more in-wall coating has lower DP and FE when WCL is relatively low. Coating technology with more on-wall coating helps to improve filtration performance, especially initial FE at fresh status. Key words: GPF, Coating Technology, Pressure Drop, Particulate Number, Filtration Efficiency, Microstructure