The effect of CO on NO reduction over Pt/Pd-based NSR catalysts at low temperature

Abstract

The present work investigates the effect of CO on NO reduction during the rich period over Pt/Pd-based NSR catalysts at low temperature. Three types of reducing agents (CO and/or H₂) are used in this research. BET and XRD are used to determine physical properties, and in situ DRIFTS explore the competitive adsorption of NO–CO and the strength of CO adsorption on the noble metal component. It is found that NO is completely reduced over Pt/Pd-based catalysts at 150 °C when H₂ is the reducing agent, while there is NO emission phenomenon when CO is the reducing agent. When H₂ and CO are reductants together, catalysts with/without Pd exhibit different NO reduction activity. In situ DRIFTS results show that there is a competitive adsorption of NO and CO on Pt/Al₂O₃ and Pd/Al₂O₃, and Pt/Al₂O₃ presents stronger CO adsorption in comparison with Pd/Al₂O₃. It is probable that the NO reduction is related to CO adsorption on the noble metal component. The adsorption strength of CO on Pt/Pd-based catalysts affects the NO reduction performance during the rich period.