Abstract:Due to the greenhouse effect of SF₆ gas, new environmentally friendly substitute gases represented by C₄F₇N, C₅F₁₀O, C₆F₁₂O, and HFO-1234ze(E) have received widespread attention. However, there is still a lack of research on the decomposition mechanism of these gas molecules when the internal temperature of the equipment increases due to local overheating or discharge conditions. To further investigate the feasibility of using new environmentally friendly gases to replace SF₆ gas, more researches are needed. This article takes HFO-1234ze(E) molecules as an example and uses the ReaxFF reactive molecular dynamics method and density functional theory to simulate and study the decomposition of HFO-1234ze(E) molecules and 20%HFO-1234ze(E)/80%CO₂ mixture gases at different temperatures from a microscopic perspective. The results show that HFO-1234ze(E) molecules have seven different decomposition pathways, and the C=O bond in CO₂ decomposes first. The C—F and C=C bonds in HFO-1234ze(E) have higher enthalpy values, making them difficult to break. As the temperature increases, the time of decomposition occurs earlier. When the temperature is below 2 000 K, HFO-1234ze(E)/CO₂ mixture gas will hardly decompose. However, when the temperature reaches 2 000 K, HFO-1234ze(E) molecule remains stable, while CO₂ molecule rapidly decomposes. At temperatures above 2 600 K, for every 2 000 K increase in temperature, about 5 more HFO-1234ze(E) molecules decompose, and about 35 more CO₂ molecules decompose, until complete decomposition is reached. The mixture gas mainly decomposes into various free radicals such as CO, O₂, C₂O₂, HF, CF₄, C₂F₆, C₃F₆, and C₃H₃F₃, among which CO is a toxic gas and HF molecules are strongly corrosive. Measures should be taken to monitor their content. The chemical properties of other decomposition products are relatively stable and environmentally friendly, and still have a certain insulating capacity. This indicates that the mixture of 20%HFO-1234ze(E) and 80%CO₂ can completely replace SF₆ gas to a certain extent, providing a theoretical basis and engineering guidance for further research on other new environmentally friendly mixed gases.