Fig. 8. SO₂-TPD profiles collected after exposure of the catalysts to SO₂ (red and blue lines) and SO₂ + O₂ (orange and light blue lines) in comparison to a reference SO₂-TPD curve of a Cu-free CHA zeolite impregnated with 20 wt% (NH₄)₂SO₄, downscaled ×10. Pre-treatment is the same as for the procedures followed by in situ XAS. The curves for the high Cu catalysts (3.2 wt% Cu/CHA) (blue and light blue lines) are downscaled ×4.