Investigation of the High Temperature Pyrolysis Behavior of Perfluorohexanone as an Environmental-Friendly Fire Extinguishing Agent

To investigate the high-temperature pyrolysis behavior of perfluorohexanone in fire extinguishers, this study utilized multiple characteristics at temperatures ranging from 500°C to 800°C under atmospheric pressure, with residence times of 2 and 5 s. The results indicated that the primary organic gas product identified was perfluoroisovaleric acid, whose production surged sharply with rising temperature, peaking at 650°C before declining significantly, falling below 10% at 800°C. The concentrations of other pyrolysis products, including perfluoropropane, hexafluoropropylene, decafluorobutane, octafluorobutene, and perfluoroisobutylene, progressively increased with temperature. By 800°C, decafluorobutane and hexafluoropropylene surpassed perfluoroisovaleric acid, becoming the most abundant organic components in the reaction gas. Additionally, a longer residence time led to a gradual increase in the production of gas products, with perfluoroisobutylene showing a particularly sharp rise, a trend that intensified with temperature. The toxicity of the organic gas products was primarily attributed to the highly toxic perfluoroisobutylene, while the inorganic gas products' toxicity was mainly due to the carbon monoxide generated during pyrolysis. Both of these toxic substances increased rapidly with higher temperatures and longer residence times. At 800°C and a residence time of 5 s, the concentration of perfluoroisobutylene in the reaction gas reached a maximum of 22.15%, while carbon monoxide levels consistently exceeded 10,000 ppm.