Effect of the support on activity of silver catalysts for the selective reduction of NO by propene

Use of zirconia, ceria–zirconia and ceria supports for Ag-based lean deNOx catalysts lowers the temperature range of activity by about 150–200 K with respect to Al2O3-supported analogues. Ex situ characterisation of the catalysts indicates that this remarkable effect is associated with a role of the support rather than Ag dispersion. The crucial role of the support is further evidenced by suppression of CO formation over these catalysts and by significant support-related differences when SO2 is added to the feed. The presence of ceria in the formulation results in an initial resistance to the deactivating effect of SO2; while the use of both zirconia and ceria–zirconia facilitates reactivation after sulphur poisoning.

Figure optionsDownload as PowerPoint slideResearch highlights▶ Activity range of supported Ag for C3H6-SCR can be tuned by the choice of support. ▶ ZrO2 improve SOx resistance and ease of regeneration of Ag catalysts. ▶ Inclusion of CeO2 in the ZrO2-based support favours SOx resistance.