Improvement of SOx-resistance of silver lean-deNOx catalysts by supporting on a CeO2-containing zirconia.

The lean-deNOx activity of Ag/Al2O3, Ag/Ce0.16Zr0.84O2, and Ag/ZrO2 was compared. The activity data showed that by supporting Ag on ZrO2-containing supports, low-temperature deNOx activity is greatly improved compared to Ag/Al2O3. TEM investigation suggested that the support is at the origin of this shift of activity to low temperature rather than in the presence of large Ag particles. More important, use of Ce0.16Zr0.84O2 and ZrO2 as supports confers improved sulphur resistance compared to Al2O3-based materials in that regeneration of the SO2-poisoned catalyst may be achieved under moderate conditions.