Technical Paper
An Assessment of the Plasma Assisted Catalytic Reactor (PACR) Approach to Lean NOx Abatement: The Relative Reducibility of NO and NO2 using #2 Diesel fuel as the Reductant
2000-10-16
2000-01-2962
The plasma assisted catalytic reactor (PACR) approach to lean NOx abatement is a two step process. The non-thermal plasma oxidizes the engine out NO to NO2, which is then reduced to N2 over a catalyst using a hydrocarbon reductant. Whereas it was once believed that the plasma itself directly reduces NOx to N2, it has been shown that the plasma's principle function is to oxidize NO to NO2. This is accomplished without oxidizing SO2 to SO3, resulting in lower sulfate particulate when compared to standard lean NOx catalysis using platinum or reducible oxide catalysts. We have performed reactor studies comparing the relative reducibility of NO2 and NO in a synthetic diesel exhaust using diesel fuel as the hydrocarbon reductant, with attention to time-on stream behavior and determination of NOx reversibly adsorbed on the catalyst. We find that at 200°C, 50% of the NO2 disappearance over Na-ZSM5 is attributable to reversible adsorption on the catalyst.