One technology proposed for reducing NOx is plasma-enhanced catalysis. It faces challenges such as degradation by sulfur and the need to design a plasma reactor that is durable enough for use on vehicles. The effect of hydrocarbon content on the selective catalytic reduction of NOx at various simulated exhaust gas temperatures for a proprietary catalyst formulation Scope of Work Researchers extended prior research by examining metal-oxide catalyst formulations that are effective in reducing NOx both at high temperatures and over a broad range of temperatures. The NOx reduction efficiency of a system consisting of a plasma reactor coupled to a catalytic converter was examined for three proprietary catalyst materials under simulated lean exhaust conditions. The data also indicate that better catalysts might necessitate higher hydrocarbon levels.
Efforts are under way to better understand how sulfur-tolerant catalysts can be improved.
Future studies will include catalyst aging, use of real diesel exhaust, increased water levels in the gas mix to test the hydrothermal stability of catalysts, and use of other hydrocarbon sources.