Development of High Performance Coated Gasoline Particulate Filter 2023-01-0388

In recent years, emission regulations have become stricter as part of the shift toward decarbonization. Particularly in Europe, the PN (Particulate Number) regulation has grown stricter, and further enhancement of PN filtration efficiency of GPF (Gasoline Particulate Filter) is required. However, as PN filtration efficiency is enhanced, pressure drop increases. There is a trade-off between PN filtration efficiency and pressure drop. In particular, coated GPF (cGPF) tends to deteriorate this trade-off relationship compared to uncoated GPF because of the coating of the catalyst. On the other hand, cGPFs have three-way performance, which can reduce the number of catalyst converters in the exhaust system. Therefore, we tried to establish a high performance cGPF by enhancing the trade-off relationship between PN filtration efficiency and pressure drop. We have used various cGPFs to analyze the coating state and substrate and characterize the functionality to understand the relationship between functions and above analysis items. The results showed that regardless of the substrate pore size, PN filtration efficiency was enhanced by reducing the neck diameter formed by the catalyst coated on the substrate. It was also found that the pressure drop was lowered by increasing the pore size of the substrate. Based on these findings, we established the concept of a high-performance cGPF, in which reduction of pressure drop is achieved by increasing the pore size of the substrate, while PN filtration efficiency is enhanced by reducing the neck diameter formed by the catalyst coated there. We have developed a prototype GPF catalyst with this concept and verified its function. This GPF achieved both PN filtration efficiency and pressure drop targets.