Lee SH  Park NK  Yoon SH  Chang WC  Lee TJ

Vol. 15,  No. 4, pp. 273-279, Dec.  2009

Hydrolytic decomposition of SF6 γ-Al2O3 AlF3 α-Al2O3

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SF6, which has a high global warming potential, can be decomposed to sulfur and fluorine compounds through hydrolysis by H2O or oxidation by O2 over solid acid catalysts. In this study γ-Al2O3 was employed as the solid acid catalyst for the abatement of SF6 and its catalytic activity was investigated with respect to the reaction temperature and the space velocity. The catalytic activity for SF6 decomposition by the hydrolysis reached the maximum at and above 973 K with the space velocity of 20,000 ml/g-cat·h, exhibiting a conversion very close to 100%. When the space velocity was lower than 45,000 ml/g-cat·h, the conversion was maintained at the maximum value. On the other hand, the conversion of SF6 by the oxidation was about 20% under the same conditions. The SEM and XRD analyses revealed that the γ-Al2O3 was transformed to α-Al2O3 during the hydrolysis and to AlF3 during the oxidation, respectively. The size of AlF3 after the oxidation was over 20 ㎛, and its catalytic activity was low due to the low surface area. Therefore, it was concluded that the hydrolysis over γ-Al2O3 was much more favorable than the oxidation for the catalytic decomposition of SF6.