Coated Gasoline Particulate Filter Technology Development to Meet China6 PN Regulation

With the introduction of stringent particulate number (PN) limits and real driving emission (RDE) requirements, gasoline particulate filters (GPFs) have been widely adopted in Europe and China. GPFs can be coated with different amounts of three-way catalyst (TWC) coating. Some applications use large amounts of washcoat (>100g/L) whereas some don’t use at all. Pressure drop (DP) and PN filtration efficiency (FE) are the top two design criteria. It is important to understand how various coating technologies can be applied to GPF technologies for optimized FE/DP performance. To study filter and coating interaction, a matrix of coated GPFs was prepared and tested for lab DP and vehicle PN based FE. The matrix includes samples with a wide range of washcoat loadings (WCLs), differing coating technologies that target more coating inside GPF filter walls (Tech A) or more on the surface of filter walls (Tech B), and GPF technologies with high and low mean pore size (MPS). Scanning electron microscope (SEM) is used to analyze the microstructure of coated filter walls and coating distribution for a better understanding of filter performance data. In general, DP and FE of coated filters are found to increase with WCL. Filters with lower MPS have higher DP and FE. Tech A has lower DP and FE when WCL is relatively low. Tech B is found to help to improve filtration performance, especially initial FE at fresh status.