Global Kinetic Study of NO Reduction by NH₃ over V₂O₅–WO₃/TiO₂: Relationship between the SCR Performance and the Key Factors

The nonselective catalytic reduction (NSCR) reaction and the catalytic oxidation of NH₃ to NO (C–O reaction) simultaneously happened during the selective catalytic reduction (SCR) of NO with NH₃ over V₂O₅–WO₃/TiO₂, especially at higher temperatures. There was an excellent linear relationship between the SCR reaction rate and gaseous NO concentration, and the intercept and slope can be used to describe the rate constant of NO reduction through the Langmuir–Hinshelwood mechanism and that through the Eley–Rideal mechanism, respectively. However, the NSCR reaction rate was nearly independent of gaseous NO concentration, and the reaction order of the C–O reaction with respect to gaseous NO concentration was much less than zero. According to the kinetic study, the relationship of the SCR performance (i.e., SCR activity and N₂ selectivity) with the key factors (for example V₂O₅ content, H₂O effect, and reactant concentration) was built, which can be used to predict the SCR performance.