Golden, S., Nazarpoor, Z., Launois, M., Liu, R. et al., "Development of Non-Copper Advanced Spinel Mixed Metal Oxides for Zero-Precious Metal and Ultra-Low Precious Metal Next-Generation TWC," SAE Technical Paper 2016-01-0933, 2016, doi:10.4271/2016-01-0933.
In the context of evolving market conditions, the three-way catalyst (TWC) design is entering an exciting new phase. It remains the main emission control strategy for gasoline powered vehicles; in the meantime a rapid period of evolving engine developments, the constrained tailpipe regulations and the material supply issues present a unique challenge to the catalyst developers. A key approach here is to achieve highly beneficial emission performance based on the ultra-low PGM levels. In this regard, we mainly focus on the materials design and have developed the advanced spinel oxides for zero precious metals (ZPGM) and synergized precious metals (SPGM) TWCs. These advanced spinel materials showed improved thermal stability compared to that of PGM based standard materials. Fundamental studies on the microstructure of spinel oxide with newly developed composition confirm the aging stability. The vehicle test data are reported for 10 g/ft3 SPGM close-coupled (CC) and 2 g/ft3 SPGM Underfloor (UF) catalysts based on the advanced spinel material. Prior to testing on tier2 bin 4 turbo gasoline direct injection (TGDi) vehicle using FTP and US06 drive cycles, the tested SPGM CC and UF catalysts are aged under standard 4-mode aging cycle. Our initial data show that SPGM UF performs as effectively as the standard high PGM technology UF catalyst, with lower weighted tailpipe NOx. In addition, SPGM CC catalyst with the low PGM loading (10 g/ft3) performs as effectively as the standard high PGM (>100 g/ft3) technology CC catalyst for NOx and CO conversions, but leaving a room for the improvement of non-methane hydrocarbon (NMHC) conversion performance.