Date of Graduation


Document Type


Degree Type



Statler College of Engineering and Mineral Resources


Mechanical and Aerospace Engineering

Committee Chair

Mridul Gautam.


Diesel oxidation catalysts (DOCs) are a viable exhaust aftertreatment alternative for alleviating regulated exhaust emissions of hydrocarbon (HC), carbon monoxide (CO), and particulate matter (PM) from diesel-fueled heavy-duty engines. This study was a part of the Diesel Emissions Control-Sulfur Effects (DECSE) program that was aimed at determining the impact of diesel fuel sulfur levels on diesel oxidation catalysts that were designed to lower brake-specific PM, HC, and CO emissions from on-highway trucks and buses in the 2002--2004 model years. The research focused on high-temperature DOCs installed on a Cummins ISM370 ESP engine, and low-temperature DOCs installed on a Navistar T444E engine to determine how the DOCs affect the various emissions, how fuel sulfur affects emissions, and how fuel sulfur poisons the catalysts over time.;The DOCs were found to affect the brake-specific PM, HC, and CO emissions. The PM emissions were not significantly affected by the DOCs when lower sulfur fuels (3 ppm and 30 ppm) were used. Brake-specific PM emissions were dramatically increased with the higher sulfur fuel (350 ppm) due to the formation of sulfates and the associated sulfate bound water. Hence, fuel sulfur affected the brake-specific PM, HC, and CO emissions from DOC equipped heavy-duty diesel engines.;Brake-specific HC emissions were eliminated by nearly 100% by the use of the DOCs. The DOCs had various reduction efficiencies ranging from 90% to 100% for CO emissions from the Navistar engine and 24% to 79% for the Cummins engine.;The DOCs were only evaluated for only 250 aging hours, which is a relatively short duration. Over this short amount of time, there was no significant evidence of the fuel sulfur poisoning the diesel oxidation catalysts.