| Article ID | Journal | Published Year | Pages | File Type |
|---|---|---|---|---|
| 46099 | Applied Catalysis B: Environmental | 2012 | 8 Pages |
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 (1 h with 10 ppm SO2 at 250 °C followed by 10 min 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.
Graphical abstractFigure optionsDownload full-size imageDownload as PowerPoint slideHighlights► Sulphur tolerance of different Ag/Al2O3 catalysts for SCR of NOx was tested. ► High SBET and high Ag load are important for high sulphur tolerance. ► SBET affects the NH3 adsorption capacity, i.e. availability of NH3 for SCR. ► A higher Ag load means more Ag clusters and particles that can be regenerated.
