Abstract: The present invention provides a polymerization inhibitor preventing the self-polymerization of TFE and the generation of a modified polymer of a polymerization inhibitor in a distillation step, particularly in a rectification step, of TFE. The present invention provides a method of distilling tetrafluoroethylene in the presence of a polymerization inhibitor comprising a cyclohexadiene compound of the formula: R1-A-R2 wherein R1 is a hydrocarbon group having 1 to 5 carbon atoms, R2 is a hydrogen atom or a hydrocarbon group having 1 to 5 carbon atoms, and A is a cyclohexadiene ring. The cyclohexadiene compound is preferably ?-terpinene or ?-terpinene.

Abstract: There is provided a process for producing hexafluoropropylene oxide which is novel and capable of achieving a higher yield. An organic phase comprising hexafluoropropylene (HFP) in an organic solvent and an aqueous phase comprising an oxygen-containing oxidizing agent in water are supplied to a small space (or microspace), preferably together with a phase transfer catalyst. The organic phase and the aqueous phase are contacted with each other in the small space, thereby reacting hexafluoropropylene (HFP) with the oxygen-containing oxidizing agent, preferably by an action of the phase transfer catalyst to give hexafluoropropylene oxide (HFPO). After the reaction, the organic phase and the aqueous phase are taken out from the small space to obtain an organic phase comprising the hexafluoropropylene oxide (HFPO).

Abstract: The present invention provides a treatment method by which a fluorinated surfactant such as PFOA can be removed from water very efficiently. The treatment method includes a step (1) of contacting a water to be treated containing 100 to 10000 ppb of a fluorinated surfactant with an activated carbon and a step (2) of obtaining a treated water containing not more than 3.0 ppb of the fluorinated surfactant. The activated carbon comprises the particles capable of passing through a 75-?m filter of not smaller than 90% by mass of the total particles.

Abstract: The present invention provides a polymerization inhibitor preventing the self-polymerization of TFE and the generation of a modified polymer of a polymerization inhibitor in a distillation step, particularly in a rectification step, of TFE. The present invention provides a method of distilling tetrafluoroethylene in the presence of a polymerization inhibitor comprising a cyclohexadiene compound of the formula: R1-A-R2 wherein R1 is a hydrocarbon group having 1 to 5 carbon atoms, R2 is a hydrogen atom or a hydrocarbon group having 1 to 5 carbon atoms, and A is a cyclohexadiene ring. The cyclohexadiene compound is preferably ?-terpinene or ?-terpinene.