Interactions of SOF/sub 2/ with molecular sieve 13X

Abstract

Interactions between the SOF/sub 2/ species and molecular sieve type 13X were studied in a SF/sub 6/ gas matrix. Adsorption experiments were performed through single or sequential exposures of pre-humidified and virgin dry samples using gas mixtures prepared at concentration levels varying from 1/spl times/10/sup 4/ to 5/spl times/10/sup 4/ ppm/sub v/. In all cases, the initial total pressure was set at 2 bar abs at 298 K. Based on the results, the 13X was found to adsorb the SOF/sub 2/ and to transform a portion of it into SO/sub 2/. This hydrolysis reaction led to an increasing amount of SO/sub 2/ in the gas phase which was monitored throughout the experiments, The kinetics observed in the early stage of initial exposure suggested an adsorption process controlled by a concentration gradient. The results also revealed that CO/sub 2/ species can be displaced by the SOF/sub 2/. When an amount of water as high as 4/spl times/10/sup 3/ ppm/sub v/ was initially present in the gas phase, the SOF/sub 2//SO/sub 2/ dynamics were not significantly modified. However, the new contaminant was found to be as effectively removed by the sieve as the SOF/sub 2/ species. On the other hand, a sieve which had been pre-humidified through extensive exposure to the ambient air released water when subjected to an SOF/sub 2/ gas mixture, pointing to a preferential SOF/sub 2/ adsorption. Considerations based on the material properties were used to explain the overall phenomena observed.