Investigation of reaction pathways and kinetics in the gas-phase noncatalytic oxidation of hexafluoropropylene

Hexafluoropropylene oxide (HFPO) is a crucial fluorinated chemical mainly synthesized from hexafluoropropylene (HFP) through the oxidation of oxygen. However, the reaction network and kinetic characteristics are not fully understood yet, resulting in a lack of theoretical basis for synthesis process improvement. Here, the free radical reaction mechanism and complete reaction network involved in the noncatalytic oxidation of HFP to synthesize HFPO was explored by density functional theory. Transition state theory was employed to calculate the intrinsic reaction rate constants for elementary reactions. Based on theoretical reaction rate ratios, reaction pathways were selected, and a simplified reaction network was derived. It was found that byproducts were formed owing to the decomposition of HFPO and subsequent reactions with excessive oxygen while oxygen tended to participate more in the main reaction under oxygen-deficient conditions. The variations in reaction pathways occurring at different HFP/oxygen molar ratios was well elucidated by comparing with experimental data. This research establishes a robust theoretical foundation for optimizing and regulating the synthesis of HFPO.