Optimization of TWC design for various engine operating conditions. 2019-01-1290
In Three Way Catalysts (TWC) for gasoline vehicles, it’s well known that Pt, Pd and Rh are used as active sites, and Al2O3 and OSC materials are used as a support. In particular, Pd and Rh are mainly used in the TWC for gasoline engine vehicles, because it required that the high thermal durability. Recently, HEV vehicles have been developed to meet the severe fuel efficiency regulation. HEV vehicles engine will be energy-efficient running than conventional gasoline vehicles. Also the engine can be controlled the fixed-point operation. So, it is considered that the stress (ex. A/F and temperature etc.) of the catalyst by engine exhaust will be changed. Therefore, the catalyst aging condition will becomes different from the conventional condition, and it is predicted that the optimum catalyst design will be changed.
In this study, to understand the optimum design for next generation TWC, it has investigated that the deterioration of TWC (Pt, Pd, Rh supported Al2O3 or OSC) after various aging conditions by using the oven which can control Rich/Lean atmosphere. The aging conditions (temperature and Rich/Lean atmosphere) were changed to simulate the various engine operating conditions. The aging samples were evaluated the physical properties and catalyst activity.
As a result, Pt catalysts were inferior in performance to Rh and Pd after the conventional high temperature aging. On the other hands, in the low temperature aging, it was confirmed that Pt/OSC catalyst showed higher performance than Pd/OSC. In additions, Pt/OSC showed most strong SMSI effect. This study will be helpful for the selection of the best design TWC (Both C/C and U/F) for various engine operating conditions.