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As the official proposal for emission regulation Euro 7 has been released by European Commission, PN above 10nm is taken into consideration for the ultrafine particulate emissions control. The challenges of GPF filtration efficiency emerge for the light-duty manufactures to meet the future emission standards. In the present study, a China 6 compliant vehicle was tested to reveal its performance over the China 6 standards and potential to meet the upcoming Euro 7. Three GPF product types (Gen 1, Gen 2, and concept Gen 3) were mounted to the tested vehicle. WLTC tests were conducted on chassis dynamometer in laboratory as well as a self-designed aggressive cycle (“Base Cycle”) tests. To explore the GPFs performance for PN emissions above 10nm against the proposed limit 6.0E11 #/km, PN emission above 10nm were measured in our laboratory tests for both engine out and tailpipe as well as the PN emission above 23nm.

With upcoming China 6b emission regulation set for full implementation in July 2023, significant efforts are being made within China OEMs to meet the stringent gaseous emission requirements, which reduce gaseous emission limits by 29 to 50% from China 6a for NOx, THC, and CO over the worldwide harmonized light-duty test cycle (WLTC). With current engine and aftertreatment technology, cold-start emissions generated in the first 200 seconds of the WLTC typically makes up most of the total tailpipe emissions result, thus the reduction of cold-start emissions becomes vital to meet regulation requirements. Besides further improvement on engine technology with optimized calibration, a common method to improve cold-start performance is to add more platinum group metals (PGM) into three-way catalyst (TWC). An alternative approach to improve cold-start performance involves using a low mass substrate to enable faster heat up of the TWC.

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).