Chemical process
AssigneeImperial Chemical Industries PLC
InventorsJohn D. Scott, Rachel A. Steven
Life of this patent
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Abstract
1,1,1,2-tetrafluoroethane (HFA 134a) is manufactured from trichloroethylene by a two-stage process comprising reacting trichloroethylene with hydrogen fluoride under superatmospheric pressure in a first reaction zone to form 1,1,1-trifluoro-2-chloroethane (133a) and reacting the 1,1,1-trifluoro-2-chloroethane with hydrogen fluoride in a second reaction zone to form 1,1,1,2-tetrafluoroethane; the entire product stream from the 133a reaction zone together with additional HF of required is fed through the 134a reaction zone. The two reaction zones may be provided within a single reaction vessel.
Claims12
A method for the manufacture of 1,1,1,2-tetrafluoroethane which comprises the steps of:
- (A) contacting a mixture of trichloroethylene and hydrogen fluoride with a fluorination catalyst under superatmospheric pressure at a temperature in the range of about 200.degree. to 400.degree. C. in a first reaction zone to form a product containing 1,1,1-trifluoro-2-chloroethane and hydrogen chloride together with unreacted starting materials,
- (B) reacting the product of step (A) with hydrogen fluoride in a second reaction zone containing a fluorination catalyst at superatmospheric pressure and a temperature in the range of about 280.degree.-450.degree. C. but higher than the temperature in step (A) to form a product containing 1,1,1,2-tetrafluoroethane, 1,1,1-trifluoro-2-chloroethane and hydrogen chloride,
- (C) separating 1,1,1,2-tetrafluoroethane and hydrogen chloride from 1,1,1-trifluoro-1-chloroethane and unreacted hydrogen fluoride,
- (D) feeding the 1,1,1-trifluoro-2-chloroethane with trichloroethylene and hydrogen fluoride to said first reaction zone (step (A)), and
- (E) recovering the 1,1,1,2-tetrafluoroethane from the 1,1,1,2-tetrafluoroethane and hydrogen chloride separated out in step (C).
Dependencies are inferred from the claim text.