A new family of automotive three-way conversion (TWC) catalyst technologies has been developed using a Precision Metal Addition (PMA) process. Precious metal (PGM) fixation onto the support occurs during the PMA step when the PGM is added to the slurry immediately prior to application to the monolith substrate. PMA slurries can be prepared with high precision and the slurry manufacturing process is greatly simplified. Further, it has been found that with the use of new generation washcoat (WC) materials, the same WC composition can be used for all three PGMs - Pt, Pd & Rh. Negative interactions between Pd and Rh in the same WC layer do not occur, providing advantages over older technologies. Thus, new WC compositions coupled with the PMA process offers precious metal flexibility. This FlexMetal family of catalyst technologies includes single layer Pd-only, Pd/Rh and Pt/Rh and dual layer bi-metal Pd/Rh and Pt/Rh and tri-metal Pt/Pd/Rh.
The new PGM placement strategies are made possible using new alumina and quaternary oxygen storage components. Extensive laboratory and dynamometer test results show that catalysts formulated using these new materials have more facile oxygen storage response characteristics than earlier catalyst technologies with twice the ceria content. FTP results further show that these technologies have excellent emission performance after aging. PGM usage comparisons are made for 2-layer systems. EURO IV level emissions are demonstrated at 20 gram per cubic feet (gcf) PGM loading.