Their aim is to devise a catalytic system that transforms NOx into harmless gases while operating on trucks at full catalytic efficiency for hundreds of thousands of miles. Designing a catalyst for NOx reduction is tougher for diesels than for gasoline engines. Combustion of diesel fuel differs appreciably from that of gasoline. For example, diesel exhaust contains much more oxygen because of excess air in the fuel-air mixture. This excess oxygen necessitates chemicals called reductants in addition to catalysts.
Some systems use a plasma in conjunction with a catalyst.
Another issue in catalytic technologies is the useful life of the catalyst before it is changed by high temperatures or chemical reactions. Oak Ridge is trying to characterize the changes that occur in catalyst materials over time and relate those changes to losses of catalytic efficiency. However, nonuniform dispersions of Pt clusters have shown poor performance. Scope of Work Oak Ridge's partners are identifying promising diesel exhaust catalysts by using theoretical insights, computer modeling, and empirical trials. Small-quantity samples of catalysts are first tested in powder form.