METHOD FOR PRODUCING TEREPHTHALIC ACID - MITSUBISHI GAS CHEMICAL CO

Title:

METHOD FOR PRODUCING TEREPHTHALIC ACID

Document Type and Number:

WIPO Patent Application WO/2017/169564

Kind Code:

A1

Abstract:

Regarding the production of terephthalic acid by: introducing, into an upper portion of a dispersion medium replacement column, a crude terephthalic acid slurry obtained by liquid-phase oxidation of a p-phenylene compound or a terephthalic acid slurry after a contact hydrogenation treatment performed on the crude terephthalic acid is introduced; and introducing a second dispersion medium as replacement from a lower portion of the dispersion medium replacement column in order to cause replacement of a dispersion medium, the present invention provides a method for producing terephthalic acid capable of maintaining the efficiency of replacement of a dispersion medium at an extremely high level, and capable of sustaining operation stably. The method for producing terephthalic acid comprises: a step for introducing, into an upper portion of a dispersion medium replacement column, a terephthalic acid raw slurry containing a dispersion medium and a crude terephthalic acid obtained by liquid-phase oxidation of a p-phenylene compound; a step for causing a rising flow of a second dispersion medium introduced from a lower portion of the dispersion medium replacement column to come into contact with the terephthalic acid raw slurry so that a slurry layer of purified terephthalic acid crystal dispersed in the second dispersion medium is formed in a lower chamber of the dispersion medium replacement column; a step for extracting the purified terephthalic acid crystal slurry from the lower chamber of the dispersion medium replacement column, and sending the slurry to a crystallization tank equipped with a means for measuring the concentration of the slurry; and a step for sending the slurry in the crystallization tank to a solid-liquid separation means to separate the terephthalic acid crystal, wherein, by adjusting the flow rate of the second dispersion medium supplied to the lower chamber of the dispersion medium replacement column, the flow rate of the purified terephthalic acid crystal slurry extracted from the lower chamber of the dispersion medium replacement column, and the flow rate of the slurry sent from the crystallization tank to the solid-liquid separation means, conditions (1)-(3) are maintained: (1) the volume V1 of the slurry in the crystallization tank is within the range of 0.050-fold to 0.80-fold with respect to the volume V0 of all the terephthalic acid slurry in the dispersion medium replacement column; (2) the position of an interface area between the terephthalic acid crystal slurry layer formed in the lower chamber of the dispersion medium replacement column and a dilute terephthalic acid slurry in a middle portion of the dispersion medium replacement column is within the variation range of ±800 mm with respect to a control target value; and (3) the concentration of the slurry in the crystallization tank is within the range of 25-40 wt%.

WO/2023/054830	METHOD FOR PRODUCING TEREPHTHALIC ACID BY USING HIGH DEGREE OF POLYMERIZATION OF POLYETHYLENE TEREPHTHALATE HAVING INTRINSIC VISCOSITY OF 0.75 DL/G OR MORE
JPS5466644	PREPARATION OF TEREPHTHALIC ACID
JP2000037633	METHOD FOR PURIFYING CRUDE AROMATIC DICARBOXYLIC ACID AND CATALYST TO BE USED IN PURIFICATION

JPH1045667A	1998-02-17
JP2008239608A	2008-10-09
JPH07149690A	1995-06-13