Process for the separation of hydrogen fluoride, 1,1-dichloro-1-fluoroethane and 1-chloro-1,1-difluoroethane from liquid mixtures thereof

Claim 2

A process for separating 1,1-dichloro-1- fluoroethane, 1-chloro-1,1-difluoroethane and hydrogen fluoride from a liquid mixture thereof comprising: (a) forming a liquid mixture comprising 1,1-dichloro-1-fluoroethane, 1-chloro-1,1-difluoroethane and HF; (b) subjecting the liquid mixture to an initial distillation to form a top product comprising 1-chloro-1,1-difluoroethane and hydrogen fluoride, and a bottom product comprising 1,1-dichloro-1-fluoroethane and hydrogen fluoride; (c) condensing the initial distillation top product to form a liquid condensate, and separating the condensate into a first upper liquid phase enriched in hydrogen fluoride relative to 1-chloro-1,1-difluoroethane and a lower liquid phase enriched in 1-chloro-1,1-difluoroethane relative to hydrogen fluoride; (d) separating the initial distillation bottom product into a second upper liquid phase enriched in hydrogen fluoride relative to 1,1-dichloro-1-fluoroethane and a lower liquid phase enriched in 1,1-dichloro-1-fluoroethane relative to hydrogen fluoride; (e) recovering 1-chloro-1,1-difluoroethane from the 1-chloro-1,1-difluoroethane-enriched lower liquid phase; and (f) recovering 1,1-dichloro-1-fluoroethane from the 1,1-dichloro-1-fluoroethane-enriched lower liquid phase.

Claim 3

A process according to claim 1 wherein the liquid mixture subject to separation is formed by reacting hydrogen fluoride in a hydrofluorination reaction mixture with a co-reactant selected from the group consisting essentially of 1,1,1-trichloroethane and vinylidene chloride, and combinations thereof.

Claim 4

A process according to claim 2 wherein the coreactant is 1,1,1-trichloroethane, and the process includes the step of removing hydrogen chloride from the liquid mixture subject to separation prior to the initial distillation.

Claim 5

A process according to claim 2 wherein the step of recovering 1-chloro-1,1-difluoroethane from the 1-chloro-1,1-difluoroethane-enriched lower liquid phase comprises distilling an azeotrope of hydrogen fluoride and 1-chloro-1,1-difluoroethane from said liquid, and recovering 1-chloro-1,1-difluoroethane from the distillation bottom product.

Claim 6

A process according to claim 4 wherein the azeotrope mixture of hydrogen fluoride and 1-chloro-1,1-difluoroethane distilled from the 1-chloro-1,1-difluoroethane-enriched lower liquid phase is recycled to and combined with the initial distillation top product.

Claim 7

A process according to claim 2 wherein the step of recovering 1,1-dichloro-1-fluoroethane from the 1,1-dichloro-1-fluoroethane-enriched lower liquid phase comprises distilling an azeotrope of HF and 1,1-dichloro-1-fluoroethane from said liquid, and recovering 1,1-dichloro-1-fluoroethane from the distillation bottom product.

Claim 8

A process according to claim 6 wherein the azeotrope mixture of hydrogen fluoride and 1,1-dichloro-1-fluoroethane distilled from the 1,1-dichloro-1-fluoroethane-enriched lower liquid phase is recycled to and combined with the initial distillation bottom product.

Claim 9

A process according to claim 2 wherein the first hydrogen fluoride-enriched upper liquid phase is recycled to and combined with the liquid mixture subject to initial distillation.

Claim 10

A process according to claim 2 wherein the second hydrogen fluoride-enriched upper liquid phase is recycled to and combined with the hydrofluorination reaction mixture.

Claim 11

A process according to claim 2 wherein the initial distillation bottom product is substantially free of 1-chloro-1,1-difluoroethane.

Claim 12

A process according to claim 10 wherein the initial distillation top product has a composition similar to the azeotropic composition of hydrogen fluoride and 1-chloro-1,1-difluoroethane, and the initial distillation bottom product has a composition similar to the azeotropic composition of hydrogen fluoride and 1,1-dichloro-1-fluoroethane.

Claim 13

A process according to claim 11 wherein the liquid mixture subject to separation contains, based upon the combined weight of 1,1-dichloro-1-fluoroethane and 1-chloro-1,1-difluoroethane in said mixture, from about 30 weight % to about 85 weight % of 1,1-dichloro-1-fluoroethane.

Claim 14

A process according to claim 12 wherein the liquid mixture subject to separation contains, based upon the combined weight of 1,1-dichloro-1-fluoroethane and 1-chloro-1,1-difluoroethane in said mixture, from about 50 weight % to about 85 weight % of 1,1-dichloro-1-fluoroethane.

Claim 15

A process for separating 1,1-dichloro-1-fluoroethane, 1-chloro-1,1-difluoroethane and hydrogen fluoride from a liquid mixture thereof, comprising: (a) from a reaction mixture for treating hydrogen fluoride with a co-reactant selected from the group consisting essentially of 1,1,1-trichloroethane, vinylidene chloride and combinations thereof, withdrawing as a reaction product stream a mixture comprising hydrogen fluoride, 1,1-dichloro-1-fluoroethane and 1-chloro-1,1-difluoroethane; (b) distilling the mixture to form a first overhead stream comprising 1-chloro-1,1-difluoroethane and hydrogen fluoride, and a first bottom stream comprising 1,1-dichloro-1-fluoroethane and hydrogen fluoride substantially free of 1-chloro-1,1-difluoroethane; (c) cooling the first overhead stream to separate said overhead stream into a first hydrogen fluoride-enriched liquid phase and a 1-chloro-1,1-difluoroethane-enriched liquid phase, and separating the two phases to form a first hydrogen fluoride-enriched stream and a 1-chloro-1,1-difluoroethane-enriched stream; (d) cooling the first bottom stream to separate said bottom stream into a second hydrogen fluoride-enriched liquid phase and a 1,1-dichloro-1-fluoroethane-enriched liquid phase, and separating the two phases to form a second hydrogen fluoride-enriched stream and a 1,1-dichloro-1-fluoroethane-enriched stream; (e) distilling an azeotrope of hydrogen fluoride and 1-chloro-1,1-difluoroethane from the 1-chloro-1,1-difluoroethane-enriched stream, and recovering 1-chloro-1,1-difluoroethane from the azeotrope distillation bottom stream; (f) recycling the azeotrope of hydrogen fluoride and 1 -chloro-1,1-difluoroethane to the first overhead stream: (g) distilling an azeotrope of hydrogen fluoride and 1,1-dichloro-1-fluoroethane from the 1,1-dichloro-1-fluoroethane-enriched stream, and recovering 1,1-dichloro-1-fluoroethane from the azeotrope distillation bottom stream; (h) recycling the azeotrope of hydrogen fluoride and 1,1-dichloro-1-fluoroethane to the first bottom stream; (i) recycling the first hydrogen fluoride-enriched stream to the reaction product stream; and (j) recycling the second hydrogen fluoride-enriched stream to the reaction mixture.

Claim 16

A process for separating 1,1-dichloro-1-fluoroethane, 1-chloro-1,1-difluoroethane and hydrogen fluoride from a liquid mixture thereof, comprising: (a) from a reaction mixture for treating hydrogen fluoride with a co-reactant selected from the group consisting essentially of 1,1,1-trichloroethane, vinylidene chloride and combinations thereof, withdrawing as a reaction product stream a mixture comprising hydrogen fluoride, 1,1-dichloro-1-fluoroethane and 1-chloro-1,1-difluoroethane; (b) distilling the mixture to form a first overhead stream comprising 1-chloro-1,1-difluoroethane and hydrogen fluoride, and a first bottom stream comprising 1,1-dichloro-1-fluoroethane and hydrogen fluoride substantially free of 1-chloro-1,1-difluoroethane; (c) cooling the first overhead stream to separate said overhead stream into a first hydrogen fluoride-enriched liquid phase and a 1-chloro-1,1-difluoroethane-enriched liquid phase, and separating the two phases to form a first hydrogen fluoride-enriched stream and a 1-chloro-1,1-difluoroethane-enriched stream; (d) cooling the first bottom stream to separate said bottom stream into a second hydrogen fluoride-enriched liquid phase and a 1,1-dichloro-1-fluoroethane-enriched liquid phase, and separating the two phases to form a second hydrogen fluoride-enriched stream and a 1,1-dichloro-1-fluoroethane-enriched stream; (e) distilling an azeotrope of hydrogen fluoride and 1-chloro-1,1-difluoroethane from the 1-chloro-1,1-difluoroethane-enriched stream, and recovering 1-chloro-1,1-difluoroethane from the azeotrope distillation bottom stream; (f) recycling the azeotrope of hydrogen fluoride and 1 -chloro-1,1-difluoroethane to the first overhead stream: (g) distilling an azeotrope of hydrogen fluoride and 1,1-dichloro-1-fluoroethane from the 1,1-dichloro-1-fluoroethane-enriched stream, and recovering 1,1-dichloro-1-fluoroethane from the azeotrope distillation bottom stream; (h) recycling the azeotrope of hydrogen fluoride and 1,1-dichloro-1-fluoroethane to the first bottom stream; (i) recycling the first hydrogen fluoride-enriched stream to the reaction product stream; and (j) recycling the second hydrogen fluoride-enriched stream to the reaction mixture.

Claim 17

A process according to claim 14 wherein the first overhead stream has a composition similar to the azeotropic composition of the mixture of hydrogen fluoride and 1-chloro-1,1-difluoroethane, and the first bottom stream has a composition similar to the azeotropic composition of the mixture of hydrogen fluoride and 1,1-dichloro-1-fluoroethane.

Claim 18

A process according to claim 14 wherein the reaction product stream subject to separation contains, based upon the combined weight of 1,1-dichloro-1-fluoroethane and 1-chloro-1,1-difluoroethane contained therein, from about 30 weight % to about 85 weight % of 1,1-dichloro-1-fluoroethane.

Claim 19

A process according to claim 16 wherein the reaction product stream subject to separation contains, based upon the combined weight of 1,1-dichloro-1-fluoroethane and 1-chloro-1,1-difluoroethane contained therein, from about 50 weight % to about 85 weight % of 1,1-dichloro-1-fluoroethane.