X-ray studies of iodine sorption in some silver zeolites

After saturation sorption, in a static system, of molecular iodine onto some silver zeolites at 130° C, powder X-ray diffraction analysis revealed sharp reflections due to crystalline α-Agl. However, this α-Agl contained only a fraction of the sorbed iodine and it seems likely that this α-Agl involves "unlocalized" ions such that a continuous three-dimensional network of α-Agl forms in the zeolite channels. Water in the zeolite channels is probably the underlying cause: heating to 200 to 300° C in air destroyed the sharp α-Agl reflections and no such reflections were observed if the sorption was carried out with the zeolites dehydrated beforehand. α-Agl formation was enhanced when the zeolite framework was broken down by heating in air at ≳ 800° C, heating in water or brine at 200° C, or γ-irradiation.