Golden, S., Nazarpoor, Z., and Liu, R., "TWC Using Advanced Spinel Materials and Prospects for BSVI Compliance," SAE Technical Paper 2017-26-0126, 2017, doi:10.4271/2017-26-0126.
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 broad context of evolving engine technology; the move to more real-world, transient testing and much tighter tailpipe emissions regulations. The specific context here is the launch of BSVI regulations for gasoline passenger cars in India.The key approach described here is to achieve highly beneficial emission performance based on low PGM levels with the emphasis on new materials technology to significantly alter the functional balance between PGM and “promoters”. We will focus on the design of materials with the spinel structure and have developed catalyst products that synergize low levels of PGM (so-called SPGM) leveraging the key properties of the advanced spinel oxides. Microstructure studies on the spinel oxide with newly developed composition confirm the aging stability [1,2]. 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. In addition transient performance of the SPGM TWC (with Spinel) will be illustrated with WLTC with a manifold mounted single CCC. Engine-out conditions at critical “stress points” will be analyzed with a view to the critical NOx conversion challenge in WLTC.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.