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Recently, there has been an upsurge in the quest for reducing emission from 2-wheelers with the introduction of Euro III emission regulations in Europe and similar regulations worldwide. While many OEMs have shifted from 2-stroke to 4-stroke, they are mostly still open loop carbureted or in some cases fuel injected. The combination of cold start fuel enrichment and high exhaust flow rates has posed challenge on the catalyst functionality for controlling the emissions of THC, CO and NOx simultaneously. This paper describes the success story of some unique, cost effective catalyst solutions for regulating THC, CO pollutants from two wheelers. This paper mainly deals with some case studies on the catalyst performance testing in the dynamic test cell as well in the actual vehicle. Several factors contributing to the catalyst performance in the cold start, ECE and EUDC mode are discussed.

Base metal oxide diesel oxidation catalyst technology having low sulfate making tendencies was evaluated using the ECE R-49 Test procedure on medium and heavy duty diesel engines and found to achieve substantial reduction of particulate, gas phase HC and CO emissions. Although the engines met the current European standards, further reduction in these emissions for vehicles operated in congested urban areas, such as buses, would have a positive impact on general air quality. A study of varying fuel sulfur levels (110-770 ppm S) showed that the catalyst was effective for control of sulfate-make such that overall particulate removal in the test was not compromised. However, it was found that lower fuel sulfur levels (< 550 ppm S) gave the best results for the ECE R-49 test which places emphasis on test modes yielding the highest exhaust temperatures.