Investigation on the Formation of Dioxins by Heavy-Duty Diesel Engines with Selective Catalytic Reduction Technology, 08-R8080

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Principal Investigators
Joseph C. Pan
Reggie R. Zhan
E. Robert Fanick

Inclusive Dates:  07/07/09 – Current

Background - By 2010, new diesel engines will be required by the U.S. Environmental Protection Agency to emit no more than 0.2 grams per brake horsepower hour (g/bhp-hr) of nitrogen oxide (NOx). To meet such a stringent NOx emission requirement, a SCR (selective catalytic reduction) technology has been developed in which NOx is reduced to N2 and water in the presence of NH3 (from the decomposition of urea) and a metal-based catalyst. Among several catalysts, copper-zeolite (Cu-Z) has been proposed for such a purpose. However, it is known based on prior research that dioxin formation is enhanced during combustions when certain metals, especially copper, are present as catalysts.

The EPA is extremely concerned about the potential dioxin emissions from heavy-duty diesel engines equipped with SCR. SwRI proposes to carry out an investigation into this matter.

Approach - SwRI is investigating dioxin formation possibilities by varying the following parameters: temperature of the exhaust; presence of chlorine in fuel, lubricating oil, and urea; with or without DOC (diesel oxidation catalysts) and DPF (diesel particulate filter); with or without Cu-Z SCR and urea.

Accomplishments - Recently initiated; no significant accomplishments to date.

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