Achieving SULEV30 Regulation Requirement with Three-Way Catalyst on High Porosity Substrate while Reducing Platinum Group Metal Loading

Fleet average SULEV30 emissions over FTP-75 must be met under full implementation of US Tier 3/LEV III emission regulation in 2025. The majority of SULEV30 certified 2021 model year vehicles are equipped with ≤ 2L displacement engines and some models adopt hybrid powertrain systems. Pickup trucks account for > 20% of passenger vehicles in the US. They could represent a quick route to meet fleet average SULEV30 targets. The newest pickup truck models are typically ULEV50 or ULEV70 certified. To reach SULEV30 or lower emission category, total tailpipe emissions must be reduced by more than 40%. Improvement of cold start emission is essential because over 70% of regulated emission is emitted during the first 60 seconds of a drive cycle with current engine and aftertreatment technology. High porosity (HP) ceramic substrate is designed to reduce thermal mass and time required to reach three-way catalyst (TWC) active temperature compared to conventional ceramic substrates. The benefit of HP substrate has been evaluated by engine bench and vehicle dynamometer tests with MY2020 SULEV70 certified pickup truck equipped with 5.3L gasoline engine. The result shows that HP TWC meets SULEV30 requirement with engineering margin. The improvement from conventional TWC is up to 30% in tailpipe emission after full useful life aging. In addition, HP TWC with reduced platinum group metal (PGM) loading achieves SULEV30 requirements; HP TWC technology could be used for cost-saving measures. Furthermore, next generation HP TWC development status is included at the end of this paper.