Reaction mechanism for NO oxidation on the soot surface using a quantum chemistry. (1st April 2022)

• Record Type: Journal Article
• Authors: Li, Zehong; Zhang, Wei; Chen, Zhaohui; Zhang, Quanchang; Yang, Xili; Mao, Shidi; Jian, Wenduo
• Is Part Of: Fuel. Volume 313(2022)
• Publication Date: 2022-04-01
• Subjects: Diesel engine -- Soot -- NO surface oxidation -- Density functional theory -- Chemical kinetics analysis; Fuel -- Periodicals; Coal -- Periodicals; Coal; Fuel; Periodicals; 662.6
• DOI: 10.1016/j.fuel.2021.123032
• Languages: English
• ISSNs: 0016-2361

Abstract

Graphical abstract: Highlights: Mechanism of NO surface oxidation is revealed by using a quantum chemistry. NO adsorption by N-down is more likely to be oxidized with O2 . The interaction between the adsorbed NO and O2 facilitates the decomposition of O2 . The generation of NO2 depends mainly on the decomposition of C(NO2 ) and C(ONO2 ). A reaction kinetics model for NO surface oxidation was constructed. Abstract: Compared with the gas phase oxidation of NO, the NO surface oxidation on soot is more effective, which is critical to keep efficient diesel particulate filter regeneration and high selective catalytic reduction conversion rates. To fill the knowledge gaps in catalytic oxidation of NO on the soot surface, it is integral to study the detailed mechanism in the NO-O2 -soot reaction. This paper explores soot surface catalytic role in changing NO into NO2 using density functional theory and chemical kinetic analysis. The results exhibit that the adsorption stability of NO on the soot sites is higher than that of O2 . The adsorbed NO interacts with O2 on the soot surface, which reduces the activation energy of C(O2 ) decomposition. The NO by N-down adsorption is oxidized readily by O2 with an energy barrier of 10.9 kJ/mol, and the reaction rate is 8.8 × 10 11 s −1 at 300 K. The formation of NO2 depends mainly on C(NO2 ) and C(ONO2 ) decomposition during surface oxidation. The NO cleavage will produce C(O) and C(N), which is difficult to be further oxidized by O2 or NO. This study reveals the mechanism for soot surface catalytic of NO oxidation, which explains the results of previous experiments for the NO-O2 -soot reaction system.