Process for treatment by liquid cyclone for production of terephthalic acid suspension having reduced impurity content

• US 4,212,995 A
• Filed: 08/08/1978
• Issued: 07/15/1980
• Est. Priority Date: 08/12/1977
• Status: Expired due to Term

• Current Assignee: Mitsui Petrochemical Industries, Ltd. (Mitsui Chemicals)
• Original Assignee: Mitsui Petrochemical Industries, Ltd. (Mitsui Chemicals)
• Inventors: Shiraki, Shigemi
• Primary Examiner(s): Siegel, Alan
• Application Number:
  US05/931,891
• Time in Patent Office: 707 Days
• Field of Search: 562/485
• US Class Current: 562/485
• CPC Class Codes: C07C 51/42 Separation; Purification; Stabilisation; Use of additives
• CPC Class Codes: C07C 51/47 by solid-liquid treatment; by chemisorption
• CPC Class Codes: C07C 51/48 by liquid-liquid treatment
• CPC Class Codes: C07C 63/26 1,4 - Benzenedicarboxylic acid

Abstract

A process for treatment by a liquid cyclone for the production of a suspension of terephthalic acid having a reduced impurity content which comprises supplying a fresh and hot lower aliphatic carboxylic acid solvent to a liquid-phase catalytic oxidation product of a p-alkylbenzene or a hot, impurity-containing suspension of terephthalic acid particles in a mother liquor containing a lower aliphatic carboxylic acid solvent, feeding the resulting mixture into a liquid cyclone, treating it in the cyclone at an elevated temperature, withdrawing an impurity-containing liquid composed mainly of said mother liquor from a withdrawal opening provided near one end of the cyclone, and withdrawing a suspension of terephthalic acid particles in a lower aliphatic carboxylic acid solvent consisting mainly of said fresh solvent from a withdrawal opening provided near the other end of the cyclone; wherein a fresh lower aliphatic carboxylic acid solvent is additionally supplied into the cyclone through an opening provided between a position apart from the suspension withdrawal opening of the liquid cyclone toward its mixture-feeding opening by a distance corresponding to about two-thirds of the distance (h_o) from the mixture-feeding opening to the suspension withdrawal opening and a position apart from the suspension withdrawal opening toward its mixture feeding opening by a distance corresponding to about one-tenth of the distance (h_o).

Claims

1. A process for treatment by a liquid cyclone for the production of a suspension of terephthalic acid having a reduced impurity content which comprises supplying a fresh and hot lower aliphatic carboxylic acid solvent to a liquid-phase catalytic oxidation product of a p-alkylbenzene or a hot, impurity-containing suspension of terephthalic acid particles in a mother liquor containing a lower aliphatic carboxylic acid solvent, feeding the resulting mixture into a liquid cyclone, treating it in the cyclone at an elevated temperature, withdrawing an impurity-containing liquid composed mainly of said mother liquor from a withdrawal opening provided near one end of the cyclone, and withdrawing a suspension of terephthalic acid particles in a lower aliphatic carboxylic acid solvent consisting mainly of said fresh solvent from a withdrawal opening provided near the other end of the cyclone;

wherein a fresh lower aliphatic carboxylic acid solvent is additionally supplied into the cyclone through an opening provided between a position apart from the suspension withdrawal opening of the liquid cyclone toward its mixture-feeding opening by a distance corresponding to about two-thirds of the distance (h_o) from the mixture-feeding opening to the suspension withdrawal opening and a position apart from the suspension withdrawal opening toward its mixture feeding opening by a distance corresponding to about one-tenth of the distance (h_o).

2. The process of claim 1 wherein the additional fresh solvent is fed along the direction of the turning flow of the terephthalic acid suspension within the liquid cyclone.

3. The process of claim 1 wherein the linear speed of feeding the additional fresh solvent is about 0.3 to about 3 times as large as that of feeding the mixture into the feed opening.

4. The process of claim 1 wherein the amount of the additional fresh solvent is about 10 to about 50% by weight based on the weight of the mixture to be fed into the cyclone.

5. The process of claim 1 wherein the fresh solvent first added to the oxidation product and the additionally supplied fresh solvent are heated at a temperature which is up to about 50°

C. higher or lower than the temperature of the hot impurity-containing suspension.