PROCESS FOR MANUFACTURE OF HIGH PURITY 1,1-DICHLOROTETRAFLUOROETHANE

摘要

A process is disclosed for producing a product comprising CCl2FCF3 substantially free of CClF2CClF2. The process includes (i) contacting a mixture of perhalogenated hydrocarbons which is essentially free of CClF2CClF2 and comprises from 20 to 80 mole percent CCl3CF3 and from 5 to 80 mole percent total of at least one compound selected from the group consisting of CCl2=CCl2, CCl3CCl2F, CCl2FCCl2F and CClF2CCl3 with HF and optionally Cl2 (provided that when the mixture comprises CCl2=CCl2, Cl2 is supplied in a mole ratio of Cl2 to CCl2=CCl2 of at least 1:2) over a fluorination catalyst at an elevated temperature no higher than 375 DEG C. to provide a product mixture comprising CCl2FCClF2 and C2Cl2F4 wherein the ratio of CClF2CClF2 to CCl2FCF3 is less than about 1:50; (ii) recovering said C2Cl2 F4 from the product mixture; (iii) isomerizing CCl2FCClF2 from the product mixture to CCl3CF3 in the presence of an isomerization catalyst; and (iv) recycling the CCl3CF3 produced by the isomerization of step (iii) to step (i). The process may be used to produce high purity CH2FCF3 when combined with the hydrodehalogenation of the high purity CCl2FCF3 from step (ii) in the presence of HF.