Adsorption behavior of γ-Al2O3 toward heptafluoroisobutyronitrile and its decompositions: Theoretical and experimental insights

Abstract

Heptafluoroisobutyronitrile (C3F7CN) has received extensive attention for replacing SF6 in high voltage electrical equipment. It is necessary to assess the suitability of traditional common adsorbent activated alumina (γ-Al2O3) used in C3F7CN based equipment as adsorbent. In this paper, C4F7 N/N2 hybrid gas discharge test was carried out on the gas insulation performance test platform, and the decomposition products mainly included CF4, C2F6, C3F8, CF3CN, C2F4, C3F6 and C2F5CN. Secondly, gas samples were collected at different periods, and the gas before and after being adsorbed byγ-Al2O3 was analyzed and compared by GC-MS. Finally, based on the density functional theory, the adsorption of gas molecular on the surface ofγ-Al2O3 was studied. The adsorption effect ofγ-Al2O3 to C3F7CN, C2F5CN and CF3CN is very strong, so it is difficult to be used as adsorbing material for C3F7CN type gas insulated equipment. However, due to the low cost ofγ-Al2O3, it can be used in waste gas treatment for new environment-friendly insulating gas.