Dynamic decomposition of arced SF6 by-products on activated alumina

The dynamic interaction of SOF₂ with activated alumina has been studied at 298 K in adsorption experiments. The SOF₂ adsorption process occurs in three distinct regimes related to the available adsorption sites on alumina. The first regime is an adsorption-reaction process where the change observed in the gas phase is essentially a sharp decrease in the amount of SOF₂. During the SOF₂ adsorption on alumina, an important fraction of the adsorbed phase is converted into SO₂. On saturation of the alumina surface with SOF₂, the amount of desorbing SO₂ starts to increase in the gas phase as the amount of SOF₂ decreases. This second regime is characterized by a competitive adsorption-desorption process which involves the adsorption of SOF₂ simultaneously with the desorption of SO₂ from a same site. The last regime consists of stabilization in the production of SO ₂ in the gas phase, which could correspond to its equilibrium with the SO₂-SOF₂ adsorbed mixture. The typical SOF₂ adsorption curve is well described by a Langmuir-type adsorption (type I) which gives an adsorption coefficient k_a/k_d≈0.4 h^-1