Development of New Coating Technology Optimized for Each Function of Coated GPF

<div class="section abstract"><div class="htmlview paragraph">In the near future, particulate number (PN) regulations, including the Euro 6 regulations, will be going into effective and becoming more stringent around the world targeted at gasoline engine vehicles.</div><div class="htmlview paragraph">There is a type of particulate filter that has used for diesel engine vehicles, as a means to satisfy PN regulations. There are two types of particulate filters. One is a “bare” or “adding-type” GPF that is uncoated with catalyst, and the other is a replaceable-type GPF that is coated with catalyst. The replaceable-type GPF (coated GPF) has advantages in terms of cost-performance, installation space, and lower level of pressure drop, compared to the uncoated GPF.</div><div class="htmlview paragraph">The three main functions required for a coated GPF are, an improvement of three-way catalytic performance, lowering of pressure drop, and PN filtration efficiency improvement. It means that they need such as the higher efficiency than a conventional three-way catalyst (TWC), lower level of pressure drop that won’t affect engine power output / fuel efficiency, and PN filtration efficiency enough to meet PN regulation. A high-level PN filtration efficiency is required to meet PN regulations.</div><div class="htmlview paragraph">The Zone-coating technology, which is utilized for TWCs, is also an effective means of improving the three-way catalytic performance of a coated GPF. The three-way catalytic performance of a coated GPF can be optimized by precious metal arrangement aiming at early warming up of the catalyst.</div><div class="htmlview paragraph">The GPF is used under higher temperatures than diesel engine and the amount of particulate matter (PM) is also less than in a diesel engine, so GPF coating in-the-wall is an effective way to reduce the pressure drop. Also, it was found that a deep coating into the wall helps maintain larger pore diameters and enlarges the flow route of the gas.</div><div class="htmlview paragraph">At the same time, coating on-the-wall also improved the PM filtration efficiency. This technology is utilized for diesel engine particulate filters (DPF) as well.</div><div class="htmlview paragraph">The combination of the above “Zone” / “in-the-wall” / “on-the-wall” coating, optimal design of GPF catalyst according to the OEM requirements (the three-way performance, the pressure drop, and the PN filtration) and the usage environment of each catalyst has become possible.</div></div>