| 摘要 |
PURPOSE:To obtain high-purity terephthalic acid useful as a raw material for a polyester, etc., with a reduced amount of energy used, by introducing a specific slurry solution of terephthalic acid to the top of a mother liquor replacing column and treating under a specific condition. CONSTITUTION:A slurry solution obtained by purifying a solution of crude terephthalic acid is introduced into the upper part of a mother liquor replacing part. A slurry solution of terephthalic acid(TA) crystal into which a replacing solvent of a first line introduced is fed from the lower part of the mother liquor replacing column at the same temperature or at <=100 deg.C, and further, a replacing solvent of a second line is fed from the lower part at 5-120 deg.C lower than the replacing solvent of the first line. Telephthalic acid (TA) crystal is precipitated, the mother liquor of the slurry solution of TA crystal introduced mainly from the top of the column and the replacing solvent of the first line are taken out. The slurry solution of the TA crystal precipitating in the column and the replacing solvent of the second line are extracted mainly from the bottom of the mother liquor replacing column and the TA crystal is separated from the slurry solution taken out from the column bottom part to give the objective high-purity terephthalic acid. |
