Influence of H-2, CO, C3H6, and C7H8 as Reductants on DeNO(x) Behavior of Dual Monoliths for NOx Storage/Reduction Coupled with Selective Catalytic Reduction

Journal article, 2019

The effects of feeding hydrogen, carbon monoxide, and propylene as reductants are analyzed in the combined NOx storage and reduction with selective catalytic reduction technology (NSR-SCR), with Pt-Ba/Al2O3 and Pt-Ba-Ce/Al2O3 monoliths as NSR catalysts, and Cu/BETA and Cu/SAPO-34 monoliths as SCR catalysts. Feed streams including CO2 and H2O mimic the real composition of the diesel engine exhaust. Also, the reaction temperature and reductant concentration are analyzed on NOx removal and product distribution at the converter outlet. H-2 is the most efficient reductant at low temperature. The reducing capacity of CO is comparable to H-2 from 300 degrees C and onward. Higher temperature (400 degrees C) is needed for propylene to be as effective reductant as H-2 or CO due to the promotion of storage and reduction reaction. Benefits in dual NSR-SCR configurations are enhanced with H-2 as reductant, due to higher internal generation of NH3 to be used in the SCR catalyst.