Research on the adsorption of environmentally friendly insulating gas C4F7N decomposed components on the surface of γ-Al2O3

Abstract

C4F7N is considered to be the most potential alternative gas for SF6. However, harmful decomposition by-products generated by the discharge or overheating faults will pose threat to safe operation and service life of gas insulated equipment (GIE). Herein, we investigated the adsorption performance of γ-Al2O3 on C4F7N and its decomposition products to evaluate the possibility of using it as by-products adsorbent or exhaust treatment material. It is found that γ-Al2O3 demonstrates superior adsorption capacity for CF4, C2F6, C3F8, C3F6, C2F4, and keeps stable after the interaction. The first-principles calculation infers that γ-Al2O3 has stronger interaction with C4F7N, C3F6 and C3F8 than that of C2F4, C2F6 and CF4. There exists obvious charge transfer between C4F7N and γ-Al2O3, which belongs to chemisorption. The interaction between F 2p orbital and C=C π orbital determines the gas-solid adsorption performance. The desorption properties were also explored and the recovery time was in order of CF4 < C2F6 < C2F4< C3F8 < C4F7N < C3F6. Overall, the γ-Al2O3 is inappropriate to be used as the adsorbent for decomposition by-products of C4F7N gas mixture-based GIE, while it can be used as exhaust treatment material for C4F7N wasted gas.