Improved Pd/CeO2 Catalysts for Low-Temperature NO Reduction: Activation of CeO2 Lattice Oxygen by Fe Doping

Long Zhang; Giulia Spezzati; Valery Muravev; Marcel A Verheijen; Bart Zijlstra; Ivo A W Filot; Ya-Qiong Su; Ming-Wen Chang; Emiel J M Hensen

doi:10.1021/acscatal.1c00564

Improved Pd/CeO₂ Catalysts for Low-Temperature NO Reduction: Activation of CeO₂ Lattice Oxygen by Fe Doping

ACS Catal. 2021 May 7;11(9):5614-5627. doi: 10.1021/acscatal.1c00564. Epub 2021 Apr 22.

Authors

Long Zhang¹, Giulia Spezzati¹, Valery Muravev¹, Marcel A Verheijen^{2

3}, Bart Zijlstra¹, Ivo A W Filot¹, Ya-Qiong Su¹, Ming-Wen Chang¹, Emiel J M Hensen¹

Affiliations

¹ Laboratory of Inorganic Materials and Catalysis, Department of Chemical Engineering and Chemistry, Eindhoven University of Technology, P.O. Box 513, 5600 MB Eindhoven, The Netherlands.
² Applied Physics, Eindhoven University of Technology, 5600 MB Eindhoven, The Netherlands.
³ Eurofins Material Science Netherlands BV, 5656 AE Eindhoven, The Netherlands.

Abstract

Developing better three-way catalysts with improved low-temperature performance is essential for cold start emission control. Density functional theory in combination with microkinetics simulations is used to predict reactivity of CO/NO/H₂ mixtures on a small Pd cluster on CeO₂(111). At low temperatures, N₂O formation occurs via a N₂O₂ dimer over metallic Pd₃. Part of the N₂O intermediate product re-oxidizes Pd, limiting NO conversion and requiring rich conditions to obtain high N₂ selectivity. High N₂ selectivity at elevated temperatures is due to N₂O decomposition on oxygen vacancies. Doping CeO₂ by Fe is predicted to lead to more oxygen vacancies and a higher N₂ selectivity, which is validated by the lower onset of N₂ formation for a Pd catalyst supported on Fe-doped CeO₂ prepared by flame spray pyrolysis. Activating ceria surface oxygen by transition metal doping is a promising strategy to improve the performance of three-way catalysts.