Excellent Oxygen Storage Capacity of Perovskite-PD Three way Catalysts
Increasingly stringent emissions controls have led to a greater emphasis on strategies designed to minimize emission during cold start. One strategy employed is that of close-coupling the catalyst to the exhaust manifold of the engine in an effort to minimize catalyst light-off time. In this configuration, the catalyst must exhibit a high degree of thermal stability. Further, since the catalyst is situated nearer to the engine, it is more liable to sense cylinder-to-cylinder variations in exhaust gas composition and thus needs to possess a wider operating window than a catalyst positioned further underbody. We have previously reported that Perovskite-Pd catalysts exhibit excellent heat resistance and have three-way catalyst activity comparable with or superior to that of Pt-Rh/ Al2O3 catalysts and Pd/Al2O3 catalysts *. Durability at high temperatures and oxygen storage capacity under large air/fuel (A/F) ratio fluctuation conditions have now been tested.