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Method of recovering unreacted alkylbenzene in process of preparing aromatic carboxyl acid

A technique for the recovery of aromatic dicarboxylic acids, which is applied in the preparation of carboxylate salts, chemical instruments and methods, and the preparation of organic compounds, and can solve the problem of inability to extract alkylbenzenes in concentration, no distillation, and large changes in the composition of intermediate extractions To achieve the effect of suppressing the loss of acetic acid, reducing the processing load, and stabilizing the composition of dehydration

Inactive Publication Date: 2010-01-20
HITACHI LTD
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

However, the current situation is that the lower limit region in this azeotropic distillation column is the region where the composition change is most obvious to the distillation section, and the slight thermal changes in the column (supply amount, supply heat, reflux amount, distillate amount, tower bottom flow amount) etc.), etc., will make the composition of the intermediate extraction change greatly, not only cannot extract the alkylbenzene at a stable concentration, but even do not distill it out at all

Method used

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  • Method of recovering unreacted alkylbenzene in process of preparing aromatic carboxyl acid
  • Method of recovering unreacted alkylbenzene in process of preparing aromatic carboxyl acid
  • Method of recovering unreacted alkylbenzene in process of preparing aromatic carboxyl acid

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Embodiment 1

[0100] In the acetic acid recovery system in the terephthalic acid manufacturing process, use the azeotropic distillation column 1 of tray type (actual plate number 80 trays), adopt the azeotropic distillation method that uses isobutyl acetate as entrainer to acetic acid for dehydration, using Figure 4 The flow process step of representation reclaims acetic acid, extracts the distillate that contains p-xylene and reclaims. Figure 5 Represent the operation flow in the acetic acid recovery system of the present invention.

[0101] Feed composition is to assume that the concentration of water collected from the production of terephthalic acid is about 20% by weight, about 46% by weight, and about 88% by weight of acetic acid recovery lines 11, 12, 13, respectively connected to the bottom of the distillation column 1 The 7th tray of the actual number of trays (the 4th tray of the theoretical number of trays), the 15th tray of the actual number of trays (the 9th tray of the theo...

Embodiment 2

[0111] Further continue the operation of the distillation tower in Example 1. At the same time, after the contents are discharged on the 50th day of Embodiment 1, the controller 24 starts the cycle again. Because the hydrocarbons containing p-xylene are accumulated without interruption, the distillation tower 1 is continued. (the 57th tray of the actual number of trays)-storage tank 3-: the circulation of the distillation column 1 (the 58th tray of the actual number of trays). The PX concentration was concentrated to 55.91 wt% on the 11th day from the restart cycle, and the PX / IBA concentration ratio increased to 1.33. In addition, the temperature of the 57th plate of the actual number of plates of the distillation column 1 at this time was 98.6 degreeC.

[0112] Then, the controller 24 performs control to interrupt the above-mentioned circulation similarly to Example 1, and recovers the distillate organic phase in the distillate storage tank 3 . In addition, the same as in E...

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Abstract

The invention discloses a non-reacted dialkyl benzene recycling method from boiled distilled acetate dehydrating tower, which comprises the following steps: adopting iso-butyl acetate as entrainer; controlling the entrainer area at 94-100 deg.c; separating the distilled liquid from bottom of liquid reserving groove; recycling organic distilled phase to entrainer area.

Description

technical field [0001] The present invention relates to a method for recovering unreacted alkylbenzenes from the process of producing aromatic carboxylic acids through the oxidation reaction of alkylbenzenes in the liquid phase using molecular oxygen gas in the presence of a heavy metal catalyst in an acetic acid solvent, in detail In other words, it relates to a method for recovering and reusing unreacted alkylbenzene from an oxidation reaction of alkylbenzene from a recovery system for acetic acid as a reaction solvent. technical background [0002] The method of producing terephthalic acid or isophthalic acid by using acetic acid as a solvent in the presence of a heavy metal catalyst to carry out liquid-phase oxidation of xylene or m-xylene with molecular oxygen gas has generally been industrialized. [0003] In the production method of these aromatic dicarboxylic acids, in the reaction step of liquid-phase oxidation of dialkylbenzene as p-xylene or m-xylene, in order to ...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): C07C15/02C07C7/04C07C51/265
Inventor 原德明伊藤博之山崎初太郎
Owner HITACHI LTD