The use of Short Time on Stream (STOS) transient kinetics to investigate the role of hydrogen in enhancing NOx reduction over silver catalysts

Sarayute Chansai*, Robbie Burch, Christopher Hardacre

*Corresponding author for this work

Research output: Contribution to journalArticle

12 Citations (Scopus)

Abstract

The role of hydrogen in promoting the reduction by ammonia of NOx on silver catalysts has been investigated using a Short Time on Stream (STOS) technique to allow differentiation between potentially reactive intermediates and relatively inactive spectator species. Under these conditions, we have used DRIFTS to identify surface nitrate species that are formed and removed on a timescale of seconds. This is in contrast to nitrate species observed under normal steady-state conditions which can continue to form over many tens of minutes. Since this timescale of seconds is very similar to the response rate at which the NH3/NOx to N-2 reaction is accelerated when H-2 is added, or decelerated when H-2 is removed, we conclude that this fast-forming and fast disappearing nitrate species is most probably adsorbed on or close to the active Ag sites. The removal of such a blocking nitrate species from the active sites can explain the effect of H-2 in greatly increasing the rate of the overall de-NOx reaction. 

Original languageEnglish
Pages (from-to)223-231
Number of pages9
JournalJournal of Catalysis
Volume295
Early online date29 Sep 2012
DOIs
Publication statusPublished - Nov 2012

Keywords

  • IN-SITU DRIFTS
  • HC-SCR
  • H-2 effect
  • Nitrates
  • LOW-TEMPERATURES
  • Ammonia
  • Ag/Al2O3
  • MECHANISTIC ASPECTS
  • HIGHER HYDROCARBONS
  • SELECTIVE REDUCTION
  • AG-ZEOLITES
  • ALUMINA CATALYSTS
  • CO/H2 REACTION
  • ACTIVITY ENHANCEMENT
  • NH3-SCR
  • STOS
  • AG/AL2O3 CATALYSTS
  • Silver

ASJC Scopus subject areas

  • Catalysis
  • Physical and Theoretical Chemistry

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