N2O formation during NOx storage and reduction using C3H6 as reductant

Abstract

N2O formation over Pt-BaO/Al2O3 catalysts was found to be involved in a complex reaction network induced by C3H6 evolutions during NOx storage reduction process. C3H6 evolutions in the rich period travelled along cracking to CxHy(ad), partial oxidation to COad and followed by NCOad production. In the lean period, residual NCOad reacting with the introduced NO/O2 led to the formation of N2O. In the rich period, N2O was originated from the chemical adsorption of NO on Pt0 surface caused by C3H6 reduction. In addition, both H2O and CO2 in the feed had significant influences on N2O formation in rich period. In the presence of H2O, high performance of water-gas shift was found at T≥300°C, and steam reforming of C3H6 occurred at T≥350°C. These reactions produced a large number of Had that facilitated NH3 production and thereby decreased N2O formation. When CO2 was introduced to the feed, CO2 reforming of C3H6 appeared at T≥300°C as a result of COad production. These parts of COad were responsible for the increase in N2O formation.