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Azeotropic distillation method for water-containing acetic acid containing unreacted alkylbenzene in aromatic carboxylic acid preparationcarbon

An aromatic dicarboxylic acid and azeotropic distillation technology, which is applied in the direction of carboxylate preparation, separation/purification of carboxylic acid compounds, distillation purification/separation, etc., can solve the problem of large changes in the composition of the intermediate extraction and the inability to extract the concentration of alkylbenzene , non-distillation and other problems, to achieve the effect of stable dehydration composition, reducing processing load and suppressing loss

Inactive Publication Date: 2013-09-04
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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  • Azeotropic distillation method for water-containing acetic acid containing unreacted alkylbenzene in aromatic carboxylic acid preparationcarbon
  • Azeotropic distillation method for water-containing acetic acid containing unreacted alkylbenzene in aromatic carboxylic acid preparationcarbon
  • Azeotropic distillation method for water-containing acetic acid containing unreacted alkylbenzene in aromatic carboxylic acid preparationcarbon

Examples

Experimental program
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Effect test

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 process steps shown are recovery of acetic acid and extraction of p-xylene containing fractions for recovery. Figure 5 It shows the operation steps for recovery of dialkylbenzene in 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 theoretical number...

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

In a recovery system for preparing the acetic acid solvent in aromatic dicarboxylic acid, the unreacted dialkyl benzene is stably recovered from an acid dehydrate tower for azeotropic distillation with high concentration, and the reutilization is carried out. The invention adopts the method that during the process of recovering the acetic acid for preparing the aromatic carboxylic acid, the unreacted dialkyl benzene is recovered by an azeotropic distillation tower taking the isobutyl acetate as an entrainer during the dehydration of the acetic acid, wherein, the alkyl benzene-containing fraction is delivered to a distillate storage tank in the azeotropic area of the azeotropic distillation tower at the temperature of ranging from 94-100 DEG C, after the aqueous phase is separated from the bottom part of the distillate storage tank, the organic phase fraction at the upper part of the distillate storage tank is circulated to the azeotropic area, the organic phase fraction is accumulated in the azeotropic distillation tower until the concentration ratio of the alkyl benzene and the entrainer reaches the target coverage with about 0.5 weight ratio to about 6 weight ratio, and the accumulated organic-phase fraction is intermittently recovered from the distillate storage tank.

Description

[0001] This application is a divisional application of Chinese Patent Application No. 200510095961.6 with the title of "Recovery of Unreacted Alkylbenzene in the Production of Aromatic Carboxylic Acids". The filing date of the original application is August 30, 2005. technical field [0002] The present invention relates to the azeotropy of hydrous acetic acid containing unreacted alkylbenzene in the process of producing aromatic carboxylic acid by oxidation reaction of alkylbenzene in liquid phase using molecular oxygen gas in the presence of a heavy metal catalyst in an acetic acid solvent Specifically, the distillation method 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. Background technique [0003] 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 o...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): C07C53/08C07C51/42C07C51/265C07C63/331C07C15/02C07C7/04
Inventor 原德明伊藤博之山崎初太郎
Owner HITACHI LTD