Investigation of simultaneous adsorption of SO2 and NO on γ-alumina at low temperature using DRIFTS.

The interaction mechanism between SO(2) and NO on γ-Al(2)O(3) was explored by diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS) and outlet response of the concentrations of NO, NO(2) and SO(2) under exposure of Al(2)O(3) to SO(2) and/or NO in the absence or presence of oxygen at 150°C. The results showed that SO(2) promoted NO oxidation and NO transformed weakly adsorbed SO(2) into strongly adsorbed species on γ-Al(2)O(3), and the presence of O(2) facilitated this transformation. An interaction mechanism between SO(2) and NO on γ-Al(2)O(3) was thus postulated. The exposure of Al(2)O(3) to SO(2) and NO in the presence of O(2) resulted in the formation of at least two types of intermediates. One type was [SO(3)NO], which decomposed to form NO(2), and the other type was [SO(3)NO(2)], which decomposed to form SO(3). The decomposition of both intermediates probably formed O vacancies replaceable by gaseous O(2).