Method of producing 1,1,1,2,2-pentafluoroethane, a method of producing 2,2-dichloro-1,1,1-trifluoroethane, and a method of purifying 1,1,1,2,2-pentafluoroethane

A method of producing 1,1,1,2,2-pentafluoroethane, in which 1-chloro-1,1,2,2,2-pentafluoroethane is removed by being converted to 1,1,1,2,2-pentafluoroethane by making a gas mixture of 1,1,1,2,2-pentafluoroethane and 1-chloro-1,1,2,2,2-pentafluoroethane, in which the content of 1-chloro-1,1,2,2,2-pentafluoroethane is not more than 15 vol % of the total amount of these pentafluoroethanes, react with hydrogen in a vapour phase in the presence of a catalyst, in which reactions are conducted in regions comprising the first reaction region wherein mainly perchloroethylene reacts with hydrogen fluoride in a vapor phase in the presence of a catalyst, and the second reaction region wherein mainly 2,2-dichloro-1,1,1-trifluoroethane and/or 2-chloro-1,1,1,2-tetrafluoroethane reacts with hydrogen fluoride in a vapor phase in the presence of a catalyst, said first reaction region being kept at a higher pressure than said second reaction region, and the content of 1-chloro-1,1,2,2,2-pentafluoroethane in the product gas of the reaction region is lowered to not more than 15 vol % by the rectification or extractive rectification, and the resulting gas is used as the gas mixture.