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Integrated process for recovering acetic acid and methyl acetate in production process of aromatic carboxylic acid

A technology of aromatic carboxylic acid and methyl acetate, applied in the field of azeotropic rectification, can solve the problems of large reflux of azeotrope, affecting stable oxidation reaction, high energy consumption in acetic acid recovery process, avoiding complicated process and reducing The effect of the reflux amount of the azeotrope and the reduction of the acetic acid content

Active Publication Date: 2014-08-20
CHINA PETROLEUM & CHEM CORP +1
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

However, the reflux rate of the process entrainer mentioned in the above-mentioned patent is relatively large, resulting in high energy consumption in the recovery process of acetic acid; in addition, the excess entrainer in the dehydration tower kettle mentioned in the above-mentioned patent is directly returned to the oxidation reactor with acetic acid The treatment method will inevitably increase the difficulty of controlling the oxidation feed and affect the stability of the oxidation reaction.
Still contain a certain amount of methyl acetate in the entrainer that refluxes in the dehydration tower, if the methyl acetate wherein can be separated, not only can improve the separation effect of dehydration tower, also can improve the economy of separating device, for above-mentioned co- Separation and recovery process of methyl acetate in boiling agent, there is no literature report at present

Method used

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  • Integrated process for recovering acetic acid and methyl acetate in production process of aromatic carboxylic acid

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0026] Terephthalic acid is produced by catalytic oxidation of p-xylene (PX) under a catalyst and a certain temperature and pressure. During the production process, the acetic acid aqueous solution cooled by the steam at the top of the reactor enters the upper part of the dehydration tower T1.

[0027] Such as figure 1 As shown, the theoretical plate number of the dehydration tower T1 is 40, the theoretical plate number of the entrainer refining column is 15, the theoretical plate number of the methyl acetate recovery tower is 10, and the theoretical plate number of the azeotropic agent separation column is 20. The acetic acid aqueous solution flow rate that enters dehydration tower is 1000kg / hr, wherein contains 75 wt% of acetic acid, contains water 24.5 wt%, contains the quality 0.5 wt% of methyl acetate, feeds from the 10th plate of dehydration tower, tower top steam (2 ) after condensation, the condensate (3) enters the phase separator V1, and the oil phase (5) in the phas...

Embodiment 4

[0031] Keep other conditions in Example 1 unchanged, change the entrainer PX reflux rate to 900kg / hr, the oil phase reflux rate and the total amount ratio entering the dehydration tower water are 3.3, and the PX content in the extraction of the dehydration tower tower kettle is 12.9% , the material first enters the 8th tray of the entrainer separation tower T4, and the acetic acid extracted from the tower top contains 1.2% water and 2.0% PX; after separation, the methyl acetate recovery tower still contains 0.01% acetic acid in the water phase, The content of methyl acetate extracted from the top of the entrainer refining tower is 98.1%, and the content of methyl acetate recovered from the top of the methyl acetate recovery tower is 96.3%.

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Abstract

The invention relates to an integrated process for recovering acetic acid and methyl acetate in a production process of aromatic carboxylic acid. The integrated process is as follows: water solution of acetic acid from an oxidation unit enters the upper part of a dehydrating tower, steam at the top of the dehydrating tower enters a condenser at the tower top for cooling, and concentrated acetic acid extracted from a tower kettle directly returns to an oxidation reactor; condensed fluid at the top of the dehydrating tower enters a phase splitter and is automatically splitted into an oil phase and a water phase, the oil phase enters an entrainer refining tower, methyl acetate is extracted from the tower top and is recovered, and the entrainer in the tower kettle returns to the top of the dehydrating tower; the water phase enters a methyl acetate recovering tower, methyl acetate extracted from the tower top and methyl acetate at the top of the entrainer refining tower are recovered together, water part in the tower kettle flows back to the top of the dehydrating tower, and part of water is extracted and treated. When the entrainer in the acetic acid of the tower kettle of the dehydrating tower is higher than 5 percent, the tower kettle material firstly enters an entrainer separating tower, the condensed acetic acid extracted from the tower top returns to the oxidation reactor, and excess entrainer is separated from the tower kettle. By utilizing the process, the quantity of the entrainer flowing back can be greatly reduced, and the oxidation reaction can be stably performed.

Description

technical field [0001] The invention relates to a method for recovering the reaction solvent acetic acid and the reaction by-product methyl acetate in the production process of aromatic carboxylic acids. The separation method mainly involved in the present invention is azeotropic rectification. Background technique [0002] Aromatic carboxylic acid is an important class of chemical intermediates, and is the basic raw material for the production of industrial products such as polyester, fiber, film, and bottles. Aromatic carboxylic acids such as terephthalic acid and isophthalic acid are generally prepared by catalytic oxidation of their corresponding alkyl-substituted aromatic hydrocarbons such as p-xylene and m-xylene. The oxidation reaction uses acetic acid as a solvent, cobalt acetate, manganese acetate, hydrogen bromide or tetrabromoethane as a catalyst, and is carried out at a certain temperature and pressure, and the process is accompanied by the generation of water. ...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): C07C69/14C07C67/54C07C63/26C07C51/16
CPCY02P20/10
Inventor 刘宗健汪洋袁浩任珉
Owner CHINA PETROLEUM & CHEM CORP
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