Insights into the promotional effect of alkaline earth metals in Pt-based three-way catalysts for NO reduction

Enhancing NO reduction efficiency of Pt-based three-way catalysts (TWCs) is very challenging due to poor NO activation ability. In this work, NO reduction performance was improved by introducing alkaline earth metals to adjust the electron environment of Pt, while the promoting effect was systematically studied. Structure-activity relationship indicated that NO reduction activity over the Pt-M/LA catalysts (M = Mg, Ca, Sr or Ba, LA = La-Al2O3) increases as the electronegativity of M decreases, and the TOF of Pt-Ba/LA is about 3 times more active than that of Pt/LA, which is attributed to more Pt0 species resulting from Pt-Ba interaction. Moreover, kinetic studies revealed that alkaline earth metals weaken the poisoning effect of CO and improve promoting effect of HCs, leading to an improved NO adsorption and an increased reaction rate of NO with CO and HCs. This study provides an insightful understanding for the promotional effect of alkaline earth metals on NO reduction over Pt-based TWCs. (c) 2023 Elsevier Inc. All rights reserved.

Automated summary

The NO reduction performance of Pt-based three-way catalysts (TWCs) was enhanced by introducing alkaline earth metals to adjust the electron environment of Pt. The structure-activity relationship showed that the NO reduction activity increased as the electronegativity of the alkaline earth metals decreased, with Pt-Ba/LA being the most active. It was found that the alkaline earth metals weakened the poisoning effect of CO and improved the promoting effect of HCs, leading to improved NO adsorption and increased reaction rate with CO and HCs.