An experimental and kinetic modeling study of NO oxidation over Pt/Al2O3 catalysts: Effects of co-fed propane and Pt particle size

NO oxidation over Pt/Al₂O₃ catalysts is crucial for optimizing SCR systems, yet the role of propane in modulating this mechanism across catalysts with varying Pt particle sizes remains unclear. Herein, we systematically investigate this mechanism using propane as a representative hydrocarbon. On Pt particles less than 2 nm, propane effectively reduces PtO_x formed during the reaction, enhancing NO oxidation. Conversely, on Pt particles larger than 4  nm, PtO_x is less reactive with propane and remains unreduced, hindering NO oxidation. According to the findings, we developed a dual-site kinetic model accounting for both metallic and oxidized Pt active sites. This model successfully captures NO oxidation activity in the presence of propane across catalysts with different Pt sizes. These findings provide insights into the catalytic behavior of DOC catalysts with different grain sizes and aid in constructing accurate kinetic models.