Adsorption Behavior of γ-Al2O3 Toward Heptafluoroisobutyronitrile and its Decompositions: Theoretical and Experimental Insights

Heptafluoroisobutyronitrile (C
₃
F
₇
CN) has received extensive attention for replacing SF
₆
in high voltage electrical equipment. It is necessary to assess the suitability of traditional common adsorbent activated alumina (γ-Al
₂
O3) used in C
₃
F
₇
CN based equipment as adsorbent. In this paper, C
₄
F
₇
N/N
₂
hybrid gas discharge test was carried out on the gas insulation performance test platform, and the decomposition products mainly included CF
₄
, C
₂
F
₆
, C
₃
F
₈
, CF
₃
CN, C
₂
F
₄
, C
₃
F
₆
and C
₂
F
₅
CN. Secondly, gas samples were collected at different periods, and the gas before and after being adsorbed by γ-Al
₂
O
₃
was analyzed and compared by GC-MS. Finally, based on the density functional theory, the adsorption of gas molecular on the surface of γ-Al
₂
O
₃
was studied. The adsorption effect of γ-Al
₂
O
₃
to C
₃
F
₇
CN, C
₂
F
₅
CN and CF
₃
CN is very strong, so it is difficult to be used as adsorbing material for C
₃
F
₇
CN type gas insulated equipment. However, due to the low cost of γ-Al
₂
O3, it can be used in waste gas treatment for new environment-friendly insulating gas.