engines are major source of nitrogen oxides (NOx). NOx, primarily nitric oxide
(NO) and nitrogen dioxide (NO2), are formed at high temperatures during diesel
fuel combustion. While neither NO nor NO2 are desirable, NO2 is the more reactive
gas associated with health problems. Both US Environmental Protection Agency
(US-EPA) and California Air Resources Board (CARB) initiated rulings for diesel
emissions retrofit technologies to limit NO2 emissions increase “slip” to 20%
over the engine baseline emissions. In this paper, an active diesel particulate
filter that reduces NO2 emissions is presented. The active diesel particulate
filter utilizes a porous sintered metal filter medium, which is divided into
pleated filter strips. These filter strips are regenerated (cleaned) by
applying direct electric heating to burn off accumulated soot. Exhaust
emissions measurements show that a degreened active diesel particulate filter
reduces NO2 by 42% from the diesel engine exhaust. The data also show that the
efficiency of NO2 emissions reduction improves with aging. Following a break-in
or “aging” period, the active diesel particulate filter achieved 96% NO2 reductions.
This far exceeds latest US-EPA and CARB verification standards on NO2.