Abstract:This article reviews the development methods and current situation of SF6 substitutes for power insulation. Its development methods include molecular design and confirmation (physical properties, safety evaluation, environmental impact evaluation, etc.) of substitutes, synthesis, and industrialization. At present, the developed SF6 substitutes include SF6 mixed gas, saturated and halogenated hydrocarbons, hydrofluoroolefins, perfluoroketones and perfluoronitriles. Among them, heptafluoroisobutyronitrile is currently the best-performing substitute for SF6 due to its excellent insulating properties. Meanwhile, the existing synthetic routes of heptafluoroisobutyronitrile are reviewed as well, of which catalytic reaction to synthesize heptafluoroisobutyronitrile with hexafluoropropylene and carbonyl fluoride as the starting materials has the advantages of high efficiency, greenness and environmental friendliness. Based on the past development process and the present situation of discovery, the future development trend of SF6 substitutes is prospected. It is proposed that future research should focus on the comprehensive development of heptafluoroisobutyronitrile application, and the development of next-generation SF6 substitutes including their green and efficient industrialization routes.
