Process for preparing polymer grade terephthalic acid
AssigneeKorea Research Institute of Chemical Technology
InventorsSang F. Park, Tae S. Chang, Young K. Lee, Kyu W. Choi
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Abstract
A process for purifying a crude terephthalic acid obtained by neutralization of the disodium terephthalate from alkali waste water from a polyester fabric-treatment process, into polymer grade terephthalic acid. The crude terephthalic acid is crushed, and fed to the kiln at 150.degree.-300.degree. C. for thermal treatment in an aqueous solution. The ammoniated, and the impurities in the solution are removed by adsorption followed by deammoniation, which may be accomplished by heating or by treatment with sulfuric acid.
Claims5
A process for purifying a crude terephthalic acid obtained by neutralizing disodium terephthalate from alkali waste water from a polyester fabric weight-reduction process, comprising:
- (a) crushing said crude terephthalic acid to a particle size in the range of 0.1 to 1.500 .mu.m;
- (b) thermally treating the crushed crude terephthalic acid particles in a kiln at 150.degree. to 300.degree. C. for oxidizing, decomposing and diffusing to outer surfaces of said particles;
- (c) combining the thermally treated particles with ammonia and water to produce an aqueous solution of diammonium terephthalate, containing impurities;
- (d) contacting said solution with an adsorbent, and filtering said solution for substantially removing said impurities therefrom;
- and
- (e) deammoniating said filtered solution and recovering terephthalic acid therefrom.
Dependencies are inferred from the claim text.