Study on the Adsorption Characteristics of ZIF-8 for C4F7N Decomposition Products

C4F7N has a low global warming potential (GWP, about 11000 of SF6) and excellent insulation performance. Under the background of global urgent demand to reduce greenhouse gas emissions, it has become an ideal substitute for SF6 gas and has attracted much attention in the field of gas insulated switchgear (GIS). However, it should be noted that C4F7N is easy to decompose under arc discharge or high temperature conditions, resulting in toxic by-products such as C2N2 and C3F8. In this paper, the adsorption characteristics of ZIF-8 on the harmful decomposition products C2N2 and C3F8 of environmentally friendly insulating gases were studied by molecular simulation. Firstly, the molecular models of C2N2, C3F8 and ZIF-8 were constructed and optimized. Then, the grand canonical Monte Carlo (GCMC) method was used to calculate the single-component and multi-component competitive adsorption isotherms. The results show that C2N2 is easy to form coordination bonds with ZIF-8 due to the presence of -CN in the single component adsorption, and the adsorption capacity is higher. In the multi-component competitive adsorption, C3F8 has a larger molecular dynamics diameter and a larger contact area with the ZIF-8 pore size, and the adsorption capacity is more dominant. In general, ZIF-8 is good for both harmful decomposition products.