Evaluation of NOx Emission Control Technologies for SIDI Engines 2002-01-1674
Spark-Ignited Direct-Injection (SIDI) engines, such as the Mitsubishi GDI family of engines, are being used by automobile manufacturers to improve fuel economy and reduce CO2 emissions. They are effective because they routinely operate in a lean combustion mode at light loads. However, three-way catalysts used in more conventional stoichiometric gasoline engine exhausts, have low NOx conversion efficiency in lean SIDI exhaust. To overcome this drawback, catalyst manufacturers have developed the NOx storage-reduction catalyst, sometimes referred to as the NOx storage catalyst, the lean NOx trap catalyst, or NOx adsorber catalyst.
The Department of Emissions Research at Southwest Research Institute (SwRI™) performed a test program for the Coordinating Research Council (CRC) of Alpharetta, Georgia, to assess “state-of-the-art” and “next generation” NOx reduction catalyst technologies with respect to their sensitivity to poisoning associated with sulfur in the fuel. This assessment focused on the sulfur tolerance of NOx reduction technologies that reportedly had the demonstrated potential to achieve the very high levels of NOx reduction that will be required to meet the Tier 2 emissions regulations.