Kinetic and Experimental Investigations on the Unimolecular Thermal Decomposition of an Eco-friendly Insulating Gas HFO-1336mzz(E)

Trans-Hexafluorodibutylene, C4H2F6 [HFO-1336mzz(E)] has been considered a promising eco-friendly insulating gas that can replace sulfur hexafluoride in power equipment. In power equipment, the insulating gas could encounter local overheating faults that are caused by rising contact resistance or insulation degradation. The gas’s thermal stability, in other words, thermal decomposition characteristics, significantly affect the equipment’s insulation performance, reliability, and lifespan. Therefore, this paper investigated the thermal decomposition characteristics of HFO-1336mzz(E) by both chemical kinetic analysis and experiments. Based on density functional theory and transition-state theory, the possible dissociation path of HFO-1336mzz(E) was explored and the energy changes were analyzed. The kinetic model was established to calculate the decomposition compositions of HFO-1336mzz(E) at different temperatures. It was found that the decomposition temperature of HFO-1336mzz(E) is about 820 K, and the main decomposition products at 1200–1600 K are CF4, HF, C3HF3, and CHF3. Then, a tube furnace heating experimental platform was built to simulate thermal decomposition, and the products of HFO-1336mzz(E) were measured at different temperatures. Both the calculation and experimental results indicate that C3HF3 and CHF3 are the two main decomposition products, which can be used as characteristic indicators for overheating faults in engineering applications