Theoretical and experimental studies on the thermal decomposition and fire-extinguishing performance of cis-1,1,1,4,4,4-hexafluoro-2-butene

Due to the environmental problems caused by the existing Halon substitutes, it is essential to explore new extinguishants with better environmental friendliness. In this study, in order to evaluate the practicability of cis-1,1,1,4,4,4-hexafluoro-2-butene (HFO-1336mzz(Z)) as a potential Halon substitution product, the thermal decomposition mechanism and fire-extinguishing performance of HFO-1336mzz(Z) were studied by using density functional theory calculation and experimental analysis. The computational results show that thermal decomposition of HFO-1336mzz(Z) would result in some products that can further react with active OH and H radicals, which are indispensable reactants in the flame and combustion. Moreover, during the interaction between HFO-1336mzz(Z) and flame, the fire-extinguishing radical CF3 would be produced, indicating the chemical-extinguishing mechanism and the pronounced fire-extinguishing performance of HFO-1336mzz(Z). To explore its actual fire-extinguishing effect, the fire-extinguishing concentration (FEC) of HFO-1336mzz(Z) on methane-air flame was measured in cup-burner. The FEC value of HFO-1336mzz(Z) is 6.84% in volume, which is lower than those of HFC-125 and HFC-116, and is slightly higher than that of HFC-236fa. Both the experimental and theoretical results suggest that HFO-1336mzz(Z) can be a promising candidate for Halon substitute.