Promoting effect of basic metal additives on DeNOx reactions over Pt-based three-way catalysts

Yuan Jing, Gang Wang, Shinya Mine, Jumpei Kawai, Ryo Toyoshima, Hiroshi Kondoh, Xiaorui Zhang, Shuhei Nagaoka, Ken ichi Shimizu, Takashi Toyao

Research output: Contribution to journalArticlepeer-review

3 Citations (Scopus)

Abstract

Pt has been economically favored over Rh and Pd. However, Pt-based three-way catalysts (TWCs) have been studied less than Pd- and Rh-based TWCs; therefore, their properties have not yet been sufficiently evaluated, especially under conditions relevant to modern three-way catalysis operation, wherein deviations from stoichiometric conditions are often encountered. In this study, we examined the promotional effect of basic metal additives in Pt/M/Al2O3 (M = Ba, La, Sr) on the efficiency of three-way catalytic reactions. The catalytic activities of the Pt/M/Al2O3 catalysts for NO, CO, and total hydrocarbons were superior to those of Pt/Al2O3; moreover, Ba enhanced the catalytic activity of Pt-based catalysts more efficiently than La and Sr. The best-performing catalyst, Pt/Ba/Al2O3, was subjected to kinetic studies and various in situ/operando spectroscopic experiments, namely, X-ray absorption spectroscopy, infrared spectroscopy, and ambient-pressure X-ray photoelectron spectroscopy (AP-XPS), to investigate the role of Ba in the NO reduction reaction. The Pt0 species loaded on Ba/Al2O3 were more electron-rich than those loaded on Al2O3, thereby promoting NO dissociation into N and O atoms, as revealed by the AP-XPS results. Moreover, the efficient formation of intermediate surface NOx species, including nitrites and nitrates, and their reactivities toward reductant gases, such as H2 or CO, were critical for promoting the effect of Ba on the NO reduction reaction.

Original languageEnglish
Pages (from-to)209-221
Number of pages13
JournalJournal of Catalysis
Volume416
DOIs
Publication statusPublished - 2022 Dec

Keywords

  • AP-XPS
  • In situ/operando spectroscopy
  • Pt/M/AlO
  • Three-way catalysis

ASJC Scopus subject areas

  • Catalysis
  • Physical and Theoretical Chemistry

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