Chromatographic Analysis and Monitoring of Fault Gases in Substation Using ZIF-8 Coated Capillary Column

Hua Mao¹Zeyao Ma²Yan Wang¹Jie Wang¹Yalong Xia¹Xiaoliang Zeng^1*Shihong Hu¹Xinsheng Lan¹Fangqiang Wang¹Lin Zhou¹Xuewen Liu³

• ¹State Grid Sichuan Electric Power Company, Chengdu, China
• ²Southwest Minzu University, Chengdu, Sichuan Province, China
• ³Gaoxin District Branch, Sichuan Shuneng Electric Power Co., Ltd., Chengdu, China

This study developed a ZIF-8-coated capillary gas chromatography column for the efficient separation of critical fault gases in electrical substations. By optimizing the carrier gas flow rate (3.5 mL/min) and column temperature (40°C), baseline separation of all components was achieved within 12 minutes, with resolution values of 0.8 and 3.8 for C₃H₆/C₃H₈ and C₂H₄/C₂H₆, respectively. The 3.4 Å molecular sieve pores of ZIF-8 preferentially retained larger hydrocarbons (e.g., C₄H₁₀) via size-exclusion effects, while its hydrophobic surface minimized non-specific adsorption of polar molecules like CO₂. The low polarity of methylimidazole ligands ensured selective retention of nonpolar and weak polar gases. Remarkable reproducibility was demonstrated by retention time relative standard deviations (RSD) <0.08% across 11 consecutive injections, confirming the coating's mechanical stability. Coupled with high-temperature resistance and rapid analysis capabilities, this column provides a reliable tool for real-time substation gas monitoring, enabling early warning of faults (e.g., arcing, overheating) and intelligent diagnostics of insulation degradation.