Unusual water-assisted NO adsorption over Pd/FER calcined at high temperatures: The effect of cation migration

Inhak Song, Konstantin Khivantsev, Yiqing Wu, Mark Bowden, Yong Wang, János Szanyi

Research output: Contribution to journalArticlepeer-review

9 Scopus citations

Abstract

Moisture contained in vehicle exhaust gas normally degrades the capacity and efficiency of Pd ion-exchanged zeolites as NOx adsorbents by competitive adsorption on active sites. Here, we report a counterexample to this general proposition, in which moisture facilitates the storage of NO as a nitrosyl complex on hydrated Pd ions in high temperature calcined FER-type zeolites. Divalent Pd2+ cations upon elevated temperature (>800 °C) calcination occupy sterically constrained cationic position in the zeolite framework, and become inactive for the adsorption of probe molecules such as NO. These ‘hidden’ Pd ions, however, are accessible by NO when the zeolite is hydrated, but readily release NO as dehydration proceeds. Combined systematic in situ infra-red data with X-ray diffraction Rietveld analyses reveal that the high temperature-induced relocation of Pd ions to more stable cationic positions located near 6-membered ring of the ferrierite cage is responsible for this behavior.

Original languageEnglish
Article number121810
JournalApplied Catalysis B: Environmental
Volume318
DOIs
StatePublished - Dec 5 2022
Externally publishedYes

Keywords

  • Cation migration
  • Ferrierite zeolite
  • NOx storage
  • Palladium
  • Passive NOx adsorber

Fingerprint

Dive into the research topics of 'Unusual water-assisted NO adsorption over Pd/FER calcined at high temperatures: The effect of cation migration'. Together they form a unique fingerprint.

Cite this