Chinese Journal of Catalysis ›› 2021, Vol. 42 ›› Issue (5): 795-807.DOI: 10.1016/S1872-2067(20)63694-4

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Promoting NOx reduction via in situ activation of perovskite supported Pd catalysts under alternating lean-burn/fuel-rich operating atmospheres

Dongyue Zhaoa, Yuexi Yanga, Zhongnan Gaoa, Mengxin Yina, Ye Tiana, Jing Zhangb, Zheng Jiangc, Xiaobo Yud, Xingang Lia,*()   

  1. aCollaborative Innovation Center of Chemical Science and Engineering (Tianjin), Tianjin Key Laboratory of Applied Catalysis Science and Technology, School of Chemical Engineering and Technology, Tianjin University, Tianjin 300072, China
    bInstitute of High Energy Physics, Chinese Academy of Sciences, Beijing 100049, China
    cShanghai Synchrotron Radiation Facility, Shanghai Institute of Applied Physics, Chinese Academy of Sciences, Shanghai 201800, China
    dCollege of Materials Science and Engineering, Jilin Institute of Chemical Technology, Jilin 132022, Jilin, China
  • Received:2020-04-26 Accepted:2020-04-26 Online:2021-05-18 Published:2021-01-29
  • Contact: Xingang Li
  • About author:* E-mail: xingang_li@tju.edu.cn
  • Supported by:
    National Natural Science Foundation of China(21878213);Scientific Research Project of Jilin Provincial Education Department(JJKH20180554KJ);Program of Introducing Talents of Disciplines to China Universities(B06006)

Abstract:

Herein, we report the excellent De-NOx performance of La0.7Sr0.3MnO3 (LSM) perovskite-supported Pd catalysts (Pd-LSM) in alternating lean-burn/fuel-rich atmospheres using C3H6 as reductant and describe the in situ activation of the Pd catalysts via metal-support interaction (MSI) tuning. The NOx reduction conversion of the Pd-LSM catalyst increased significantly from 56.1% to 90.1% and the production of N2O was suppressed. Our results demonstrated that this behavior was mainly attributed to the in situ transformation of Pd2+ into Pd0 during the reaction. The generated Pd0 species could readily activate the C3H6 reductant and achieve an eight-fold higher turnover frequency than Pd2+ for the reduction of NOx. Moreover, excessive MSIs inhibited the in situ generation of Pd0, and thereby, lowered the De-NOx activity of the catalyst even at high Pd dispersion. In addition, the Pd-LSM catalysts exhibited much higher S tolerance than conventional Al2O3-supported catalysts. Our study provides a new approach for analyzing and designing highly active metal catalysts operated under dynamic alternating oxidizing/reducing atmospheric conditions.

Key words: Lean-burn, NOx reduction, Metal-support interactions, In situ activation, Pd