Fluoroolefins represented by the formula: CF3(CX2)nCF═CH2, the formula: CF3(CX2)nCH═CHF, or the like, are compounds that have a useful structure as various functional materials, solvents, refrigerants, blowing agents, and monomers for functional polymers or starting materials of such monomers. For example, fluoroolefins are used as monomers for modifying ethylene-tetrafluoroethylene copolymers. Further, of the fluoroolefins mentioned above, the compound represented by CF3CF═CH2 (HFO-1234yf) and the compound represented by CF3CH═CHF (HFO-1234ze) have recently gained attention because they offer promising prospects as refrigerants with low global-warming potential.
As one of the processes for producing fluoroolefins represented by the formulae above, many methods have been reported regarding a process in which a starting material chlorine-containing alkane or chlorine-containing alkene having the same number of carbon atoms as that of a target fluoroolefin is reacted with a fluorinating agent such as an anhydrous hydrogen fluoride in the presence of a catalyst (Patent Literature 1 to 6). In this process, a chromium oxide catalyst, antimony catalyst, or the like is used as a catalyst. In particular, it has been reported that an amorphous chromium oxide catalyst is effective (Patent Literature 6). Further, when an amorphous chromium oxide catalyst is used, a method of entraining O2 or the like with a reactant to maintain the catalyst activity has been reported. However, in this method, a side reaction of the entrained O2 with the reactant sometimes produces CO2 as a by-product, or produces several by-products other than CO2, which cannot be converted into target products. This causes problems such as a decrease in the yield of target fluoroolefin, complications in a purification step, and a rise in the costs of the equipment used in the purification step.