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Method for azeotropic distillation

A technology of azeotropic distillation and azeotrope, which is used in chemical instruments and methods, separation/purification of carboxylic acid compounds, preparation of organic compounds, etc. Effect

Active Publication Date: 2008-10-15
MITSUBISHI RAYON CO LTD
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  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

In particular, azeotropic distillation is not conducive to producing low-pressure vapor if the temperature of the distillate vapor is lowered compared to ordinary distillation without an entrainer

Method used

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Embodiment 1

[0085] The acetic acid solution containing p-xylene and catalyst (acetic acid solution of cobalt acetate and manganese acetate, and hydrogen bromide), the separated mother liquor recycled by the solid-liquid separation step of the next stage, and air are continuously supplied to the stirred tank, And the oxidation reaction was carried out by adjusting the liquid level so that the residence time was 1 hour at an operating temperature of 190° C. and an operating pressure of 1.23 MPa (absolute pressure). In addition, the distillate vapor was finally cooled to 40° C. by a multi-stage condenser, and the operation was performed by adjusting the oxygen concentration in the exhaust gas to 2.5 vol%. In addition, condensates obtained from the respective condensers were collected together and returned to the oxidation reactor, and a part thereof was recovered so that the concentration of water in the mother liquor of the slurry recovered from the reactor was 10 wt%. The slurry concentrat...

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Abstract

A method, wherein a mixture to be distilled containing water, acetic acid and methyl acetate is subjected to an azeotropic distillation with an azeotropic agent having the property to undergo azeotropic distillation with water, is provided. A method of azeotropic distillation, wherein respective components of water, acetic acid and methyl acetate are separated by distallation through the steps of (1) to (5): (1) a step of distilling a mixture to be distilled containing water, acetic acid and methyl acetate with an azeotropic agent under such a pressure wherein the top of a column has a pressure higher than atmospheric pressure, to separate the mixture into a bottom recovery fraction containing acetic acid and a top distillate vapor containing water, methyl acetate and the azeotropic agent, (2) a step of condensing the top distillate vapor obtained in the above step (1), (3) a step of releasing the pressure of the condensed liquid obtained in the above step (2), to vaporize methyl acetate for recovery, (4) a step of subjecting the residual liquid in the step (3) to a liquid-liquid separation into a water phase and an oil phase, and (5) a step of feeding the oil phase obtained in the above step (4) to the above step (1) as the azeotropic agent.

Description

technical field [0001] The invention relates to a method for azeotropically distilling a mixture containing water, acetic acid and methyl acetate to be distilled by using an azeotropic agent which azeotropes with water. Background of the invention [0002] In the steam formed during the process of oxidizing p-xylene to terephthalic acid with acetic acid as a solvent, and in the mother liquor and its steam obtained by solid-liquid separation of its condensate, reaction product slurry, etc., there are Methyl acetate formed by disproportionation reaction, etc. [0003] The acetic acid solvent is usually recovered from the mixture by dehydration distillation. In this distillation method, since the relative volatility is close to 1, the separability of water and acetic acid is poor, so the method of azeotropic distillation using an entrainer that azeotropes with water is adopted. In this azeotropic distillation method, if the methyl acetate contained in the above-mentioned mixt...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): C07C51/46C07C53/08C07C63/26C07C67/54C07C69/14
CPCC07C67/54C07C51/46C07C53/08C07C69/14
Inventor 沼田元千矶贝隆行渡边隆文
Owner MITSUBISHI RAYON CO LTD
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