Mikrochim. Acta [Wien] 1988, II, 15--18 Mikrochimica Acta 9 by Springer-Verlag 1988 An FT-IR Study of Adsorption of Sulfur Dioxide on Alpha- and Gamma-Alumina Peter H. Berben 1,*, Menno J. Kappers 2, and John W. Geus 2 1 VEG-Gasinstituut n.v., P.O. Box 137, NL-7300 AC Apeldoorn, The Netherlands 2 Department of Inorganic Chemistry, University of Utrecht, Croesestraat 77", NL-3522 AD Utrecht, The Netherlands Abstract. In the Claus process hydrogen sulfide reacts to elemental sulfur. Because the Claus reaction is thermodynamically limited, sulfur compounds are still present in Claus tailgas. To avoid air pollution, the tailgas has to be treated. Alfa- and gamma-alumina are being used either as a catalyst or as a support for an active component in the Claus process and some tailgas treatment processes. In order to elucidate the mechanism of the Claus reaction, the adsorption of sulfur dioxide on both of the above aluminas was investigated using Fourier transform infrared spectroscopy. Different adsorbed species displaying a different heat of adsorption were detected. A broad band near 3500 cm -1 is associated with the basic hydroxyl groups. This band is assigned to a hydrogen bond between the surface of alumina and a bisulfite species. As bisulfite species are reactive towards hydrogen sulfide, we assume that bisulfite species are active intermediates on alumina in the Claus reaction. Key words: desulfurization, oxides, bisulfite, Claus reaction. In the Claus process hydrogen sulfide reacts with sulfur dioxide to elemental sulfur. The sulfur dioxide is produced by previous oxidation of one third of the hydrogen sulfide flow with molecular oxygen. The extent of the reaction between hydrogen sulfide and sulfur dioxide is thermodynami- cally limited. To avoid emission of sulfur compounds, the tailgas of the Claus process must thus be treated. Catalytic processes to remove the remaining sulfur compounds out of the tailgas have been developed. In the Claus process and some tailgas treatment processes y- and o~-alumina are being used either as a catalyst or as a support for an active component. * To whom correspondence should be addressed