Manufacture of halogenated compounds
AssigneeImperial Chemical Industries PLC
InventorStephen E. Potter
Life of this patent
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Abstract
Manufacture of 1,1,1,2-tetrafluoroethane by reacting 1,1,1-trifluoro-2-chloroethane with hydrogen fluoride in the presence of a chromium oxide catalyst and removing 1,1-difluoro-2-chloroethylene contaminant from the resulting impure asym tetrafluoroethane product by passing the impure product with hydrogen fluoride over a chromium oxide catalyst at much lower temperatures than are used in the manufacturing process.
Claims10
A process for the manufacture of 1,1,1,2-tetrafluoroethane which comprises reacting in the vapour phase at elevated temperature a haloethane of formula CX.sub.3 CH.sub.2 Y wherein X is bromine, chlorine or fluorine and Y is chlorine with hydrogen fluoride in the presence of a catalyst which is chromium oxide or which is at least in part basic chromium fluoride and wherein the 1,1,1,2-tetrafluoroethane product containing 1,1-difluoro-2-chloroethylene as impurity is brought together with hydrogen fluoride into contact with said catalyst which is chromium oxide or which is at least in part basic chromium fluoride at a temperature in the range 100.degree. C. to 275.degree. C. whereby said haloethylene content is reduced.
A process as claimed in any of the preceding claims wherein a chromium oxide catalyst is employed in the manufacture and purification process which is obtained by treating a chromium hydroxide paste in an atmosphere comprising 10 to 100 molar percent by weight of steam at a temperature of 50.degree. C. to 180.degree. C. for at least one hour and subsequently drying and calcining the product.
A process for the reduction of 1,1-difluoro-2-chloroethylene impurity contained in 1,1,1,2-tetrafluoroethane which comprises treating the impure 1,1,1,2-tetrafluoroethane with hydrogen fluoride in the presence of a catalyst which is chromium oxide or which is at least in part basic chromium fluoride at temperatures in the range of 100.degree. C. to 275.degree. C. whereby said haloethylene content is reduced.
Dependencies are inferred from the claim text.