Optimisation of Ag loading and alumina characteristics to give sulphur-tolerant Ag/Al2O3 catalyst for H2-assisted NH3-SCR of NOx

Sebastian Fogel, Dmitry E. Doronkin, Pär Gabrielsson, Søren Dahl

Research output: Contribution to journalJournal articleResearchpeer-review

Abstract

A series of Ag/Al2O3 catalysts with different alumina precursors and different Ag loadings were tested for H2 assisted NH3-SCR of NO. The catalysts were characterised (BET, XRD, NH3-TPD, ICP-OES, TEM and UV–vis spectroscopy) and tested as fresh catalyst, during long-term cycling tests with SO2 present and after the sulphur testing. The aim was to find an optimal configuration of the Ag/Al2O3 catalyst for automotive applications. Catalysts with a high sulphur tolerance during long-term SO2 cycling (1h with 10ppm SO2 at 250°C followed by 10min regeneration at 670°C, repeated until no difference between cycles was seen) were demonstrated. The high sulphur tolerance and activity was attributed to high surface areas of the catalyst supports, together with a high Ag loading. The high surface area allows a larger NH3 storage on the surface which is previously reported necessary for the SCR reaction. A higher Ag loading will affect the state of Ag by increasing the ratio of Ag-clusters and particles to highly dispersed Ag ions. SO2-poisoned Ag-clusters and particles can be regenerated by the high temperature treatment in the deNOx feed, highly dispersed Ag ions cannot.

Original languageEnglish
JournalApplied Catalysis B: Environmental
Volume125
Pages (from-to)457-464
ISSN0926-3373
DOIs
Publication statusPublished - 2012

Keywords

  • Ag/Al2O3
  • NH3
  • SCR
  • H2
  • Sulphur tolerance

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