Method for producing terephthalic acid and terephthalic acid
A technology of terephthalic acid and a manufacturing method, which is applied in the preparation of carboxylate, chemical instruments and methods, preparation of organic compounds, etc., can solve the problems of terephthalic acid residue, increased reaction time, time required for loading and unloading, etc.
Active Publication Date: 2008-06-11
MITSUI CHEM INC
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- Application Information
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Problems solved by technology
Conversely, if the proportion of large-diameter particles exceeding 250 μm is excessively increased, terephthalic acid tends to remain as an unreacted component during the direct polymerization method. wait, it's clear
On the other hand, if the proportion of the fine powder below 50 μm is increased too much, there is a problem that it takes time to load and unload the product or transport it.
Method used
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Embodiment 1
[0060] The inventors of the present invention will specifically describe experiments during continuous operation with respect to the aforementioned former conventional manufacturing apparatus and the manufacturing apparatus of the third embodiment of the present invention.
[0061] A high-purity terephthalic acid aqueous slurry with a particle size distribution of 74 to 149 μm was adjusted, and the slurry was pressurized in a dissolving tank and completely dissolved at 220°C from the terephthalic acid aqueous solution, using three series of the same capacity. crystallization tank for crystallization.
[0062] In this case, let the inner diameter of the first crystallization tank be D and the blade diameter be R, the blade diameter R using stirring is 0.5D, and the shape of the blade is that the length in the vertical direction on the central portion side is A stirring blade composed of 6 blades of 0.5R and a length in the vertical direction of the blade tip portion of 0.15R. ...
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Abstract
A method for producing terephthalic acid wherein an aqueous terephthalic acid solution is purified with a platinum group metal catalyst and then terephthalic acid is crystallized from the resultant aqueous solution, which comprises carrying out the crystallization in an agitating vessel which has, in the bottom portion thereof, an agitating blade being formed in a shape of an approximately trapezoidal plate and being capable of changing a rotating number; and a terephthalic acid product having a narrow particle size distribution. The above method allows the production with good efficiency of terephthalic acid crystals which are excellent in powder characteristics, slurry characteristics and reactivity, and can be controlled with respect to the particle size distribution.
Description
technical field [0001] The present invention relates to a method for producing terephthalic acid, and more specifically, relates to a method for producing terephthalic acid suitable as a raw material for producing polyesters such as polyethylene terephthalate. The present invention also relates to terephthalic acid having a narrow particle size distribution produced by the production method. Background technique [0002] The crude terephthalic acid obtained by the oxidation of p-xylene usually contains a large amount of various impurities including 4-carboxybenzaldehyde (abbreviated as "4CBA"), and after purification, it is used as polyester raw materials to use. [0003] As a method for purifying such crude terephthalic acid, a method of dissolving crude terephthalic acid in an aqueous solvent and contacting it with a platinum group metal catalyst under high pressure and high temperature for purification is known (for example, a special Kaihei No. 6-329583), several purif...
Claims
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IPC IPC(8): C07C51/43C07C63/26C07C51/487
CPCC07C51/487C07C51/43C07C63/26B01D9/0059B01J23/40C07C2523/40
Inventor 加藤一彦
Owner MITSUI CHEM INC