Abstract: The effect of SO₂ on the catalytic oxidation of NOover γAl₂O₃ support was studied at temperature of 423 K. It was found that the activity of γAl₂O₃ for the oxidation of NOto NO₂ was enhanced temporarily in the presence of SO₂. The adsorption capacity of NOand SO₂ was also promoted by each other. The interaction between γAl₂O₃ and SO₂ was discussed by using of various material characterization techniques such as TPD, FTIR, XRD, BET, solid acid detection and so on. After long time reaction in the presence of SO₂, no solid nitrate and sulfate were detected in γAl₂O₃, but the Lacid and Bacid concentrations were increased. TPDspectra show that the desorption peak of NO₂ species in the range of higher temperatures mounts up after SO₂ coadsorption with NOand O₂ on γAl₂O₃. FTIRresults indicate that different kinds of adsorption species are present on the surface of γAl₂O₃ and the main NOadsorption species are changed by SO₂ coadsorption. An active surface species, which may be responsible for the higher oxidation activity of γAl₂O₃ in the presence of SO₂, is supposed to be formed on the surface of γAl₂O₃ via SO₂, NO, O₂ and surfaceadsorbed hydroxide. The activity of γAl₂O₃ decreases while the surface of γAl₂O₃ is covered gradually by a strong adsorption of SO₂.

Key words: Catalytic oxidation of NO, Effect of SO₂, γAl₂O₃, Deactivation of catalyst