Promoted Fe/ZSM-5 catalysts prepared by sublimation: De-NOx activity and durability in H2O-rich streams

Hai Ying Chen, Wolfgang M.H. Sachtler

Research output: Contribution to journalArticlepeer-review

147 Scopus citations

Abstract

Fe/ZSM-5 catalysts with an Fe/Al ratio ≅ 1.0, were prepared by sublimation of FeCl3 intoH/ZSM-5. They display high activity and durability for the selective catalytic reduction of NOx to N2, both in dry and wet gas flows. These catalysts have now been modified by exchanging a second cation into the zeolite. Mere neutralization of zeolite protons by Na+ lowers the selectivity for NOx reduction to N2, but the cations Ce3+ and La3+ act as true catalyst promoters. With isobutane as the reductant in a simulated vehicular emission gas, almost 90% of NOx is reduced to NT at 350°C over the La-promoted catalyst. The presence of 10% H2O in the feed does not impair the catalyst performance at high temperature; in the temperature region below 350°C it even increases the N2 yield. The beneficial effect of La is due to its lowering of the catalyst activity for the undesired combustion of the hydrocarbon. No signs of zeolite destruction are evident after 100 h TOS in a wet gas flow at 350°C. Carbonaceous deposits causing a slight deactivation are easily removed in an C2/He flow at 500°C; this in situ regeneration fully restores the original activity.

Original languageEnglish
Pages (from-to)125-130
Number of pages6
JournalCatalysis Letters
Volume50
Issue number3-4
DOIs
StatePublished - 1998
Externally publishedYes

Keywords

  • Catalyst durability
  • De-no in lean burn emissions
  • Promoted Fe/ZSM-5
  • SCR of no

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