Global kinetic model of NO oxidation on Pd/γ-Al2O3 catalyst including PdOx formation and reduction by CO and C3H6

• Published in: Applied catalysis. B, Environmental Vol. 260; p. 1
• Main Authors: Buzková Arvajová, Adéla, Boutikos, Panagiotis, Pečinka, Rudolf, Kočí, Petr
• Format: Journal Article
• Language: English
• Published: Amsterdam Elsevier B.V 01.01.2020; Elsevier BV
• Subjects: Aluminum oxide; Automotive exhaust gas aftertreatment; Catalysts; Catalytic activity; Converters; Deactivation; Diesel oxidation catalyst; Durability; Mathematical modeling; Nitrogen dioxide; NO oxidation; Oxidation; Oxidation rate; Oxides; Palladium; Platinum; Ramps; Thermal stability; Transitional aluminas; Automotive exhaust gas aftertreatment; NO oxidation; Mathematical modeling; Deactivation; Diesel oxidation catalyst
• ISSN: 0926-3373; 1873-3883
• DOI: 10.1016/j.apcatb.2019.118141

[Display omitted] •PdOx formation affects NO oxidation rate on Pd/Al2O3 diesel oxidation catalyst (DOC).•NO2 yield gradually decreases with the growing PdOx coverage.•The transients studied during both isothermal deactivation and temperature ramps.•Formed Pd oxides are stable but can be reduced by CO or HC under lean conditions.•Global kinetic model developed, including the impact of O2, NO2, CO and HC on PdOx coverage. Pd is often used in diesel oxidation catalysts (DOC) together with Pt to ensure thermal stability and durability. Besides CO and hydrocarbon oxidation, NO oxidation is important for the function of subsequent converters in the exhaust line, such as SCR and DPF. Though Pt sites exhibit a significantly higher NO oxidation rate, Pd also provide some catalytic activity for this reaction and therefore affect the overall NO2 yield in DOC. Palladium oxides (PdOx) formation decreases the NO oxidation activity like PtOx. We present a global kinetic model for Pd/γ-Al2O3 catalyst considering standard DOC reactions extended with the PdOx formation and its influence on the NO2 yield. The dynamics of transition between the metallic Pd and oxidized PdOx state is studied in repeated temperature ramps and isothermal deactivation experiments, revealing the individual impact of O2 and NO2. The model describes well a dual NO oxidation light-off behavior observed in the experiments.