Study of the adsorption of sulfur dioxide on dealuminated zeolites Y by thermal desorption and powder X-ray diffraction

Sulfur dioxide is adsorbed on zeolites Y in two forms. The amount of the stable form (T_des=350–390 K) changes in proportion to the sodium content in the zeolite The stable form is localized in a large void at a distance of 1.8 å from the S_II position and causes redistribution of sodium cations. The weakly bound form (T_des=286–300 K) makes the main contribution to the adsorption of SO₂ on highly siliceous zeolites Y and is formed by adsorbate-adsorbate interaction, and it is apparently delocalized in a large void. Out-of-framework aluminum compounds that are formed during dealumination decrease the free volume of the zeolite without changing the nature of interaction of SO₂ with the zeolite.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 3, pp. 535–541, March, 1991.