Microkinetic Modeling of HC-SCR of NO to N₂, N₂O, and NO₂ on Pt Catalysts in Automotive Aftertreatment

One of the main pollutants in automobile engine exhausts is NO. Hydrocarbon-based selective catalytic reduction (HC-SCR) is one of the most preferred methods to reduce NO at the expense of unburned hydrocarbons, which are also present in automobile exhausts. In this study, we have developed a detailed kinetic model and analyzed the selectivity of NO reduction to various products (N₂, N₂O, and NO₂). The optimal operating conditions for the maximum reduction of NO to N₂ are also explored. Various phenomena including coking and the oxygen-rich nature of the catalyst surface are found to occur as the amount of oxygen in the inlet is varied. The influence of O₂ and temperatures on the selectivity of NO reduction is discussed in detail.