The LDV gasoline emission regulation is set to be tightened for Euro7. In particular, the particulate number (PN) requirement has been significantly tightened requiring a GPF with extra - high filtration efficiency to meet the target requirement.
In order to meet the stricter PN requirements, GPF substrate material improvement is necessary. However, conventional GPF material improvement for high filtration efficiency will increase the filter backpressure significantly. The relationship between pressure drop and CO2 emission is difficult to quantify but high pressure drop can potentially increase the CO2 emission. Therefore, Membrane Technology (MT) is the key to break through the trade-off between filtration performance and pressure drop. MT is thin and dense layer of small grains applied on the GPF surface. MT application can increase particulate filtration efficiency significantly with minimal pressure drop increase. To make MT work effectively, membrane conditions need to be optimized. In addition, the effect of each condition on GPF filtration performance needs to be verified.
On the other hand, it is also important to maintain GPF filtration performance, membrane durability and robustness under all GPF operating conditions and Full Useful Life of the vehicle. In order to achieve the membrane durability and robustness, membrane grains need to be adhered to the GPF surface and GPF performance needs to be evaluated for all GPF operating conditions.
This paper shows the results of membrane technology optimization for maximizing GPF performance, particulate filtration performance of GPF with MT, and the durability performance of MT.