Fluorocarbon purification process
AssigneeE. I. Du Pont de Nemours and Company
InventorsLeo Ernest Manzer, V. N. Mallikarjuna Rao
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Abstract
A halocarbon product made from the reaction of excess hydrogen fluoride with a halocarbon, containing excess hydrogen fluoride as an azeotrope is purified by fluorination in the presence of additional halocarbon or halo-olefin.
Claims20
A process wherein a halogenated hydrocarbon starting material is reacted with HF to produce a fluorination product including at least one product compound selected from the group consisting of saturated chlorofluorohydrocarbons and fluorohydrocarbons which contain from 1 to 6 carbon atoms, characterized by:
- (1) fluorinating said starting material with HF to provide an initial product mixture containing HF and said at least one product compound, the amount of HF for said fluorination being in sufficient excess to azeotropically combine with said at least one product compound;
- (2) distilling the initial product mixture of (1) to remove HCl and to recover said at least one product compound along with the HF which is azeotropically combined therewith;
- (3) adding additional halogenated hydrocarbon material selected from (i) halocarbons of the formula CaHbClcFd where a is 1 to 6, b is 0 to 13, c is 1 to 13, and d is 0 to 13, provided that b+a+d equals 2a+2 when the compound is acyclic and 2a when it is cyclic, and (ii) halo-olefins of the formula CaHbClcFd where a is 2 to 6, b is 0 to 11, c is 1 to 11, and d is 0 to 11, provided b+c+d equals 2a when the compound is acyclic and 2a−2 when it is cyclic, to the azeotropic composition recovered in (2) to produce a reactive mixture, the amount of said additional halogenated hydrocarbon material being a molar amount greater than the HF in said azeotropic composition and said additional halogenated hydrocarbon being additional starting material;
- and
- (4) reacting the reactive mixture of (3) in the presence of a fluorination catalyst under fluorinating conditions to produce a product mixture with reduced HF content, thereby utilizing azeotropically combined HF.
A method for purifying 1,1,1,2-tetrafluoroethane product containing (a) CF3CH2F, (b) HF in an amount sufficient to azeotropically combine with said CF3CH2F, and (c) easily separated material including HCl, comprising:
- separating HCl from said product;
- adding CCl2═CHCl to provide a reactive mixture containing CF3CH2F, HF and CCl2═CHCl;
- and bringing the reactive mixture into contact with a fluorination catalyst in the vapor phase so as to decrease the hydrogen fluoride content.
Dependencies are inferred from the claim text.