Method for preparation of acetic anhydride and acetic acid by means of carbonyl synthesis of methyl acetate and methanol azeotrope and method for separation

A methyl acetate and oxo synthesis technology, which is applied in the separation/purification of carboxylic acid compounds, chemical instruments and methods, and preparation of carboxylic anhydrides, can solve the problems of difficult separation and large steam consumption, and achieve short process flow and protection Environmental and emission reduction effects

Active Publication Date: 2012-03-21
ANHUI WANWEI UPDATED HIGH TECH MATERIAL CO LTD
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AI Technical Summary

Problems solved by technology

The production of one ton of polyvinyl alcohol requires 1.5 tons of methyl acetate and methanol azeotrope as a by-product. The methyl acetate and methanol azeotrope cannot be used in the production of polyvinyl alcohol,

Method used

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  • Method for preparation of acetic anhydride and acetic acid by means of carbonyl synthesis of methyl acetate and methanol azeotrope and method for separation
  • Method for preparation of acetic anhydride and acetic acid by means of carbonyl synthesis of methyl acetate and methanol azeotrope and method for separation
  • Method for preparation of acetic anhydride and acetic acid by means of carbonyl synthesis of methyl acetate and methanol azeotrope and method for separation

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Embodiment Construction

[0023] In conjunction with the accompanying drawings, the specific implementation process is described as follows:

[0024] (1) Preparation of rhodium catalyst

[0025] RhI 3 or RhCl 3 Put it into the preparation kettle, add acetic acid (HAc), control the Rh concentration at 1000-2000ppm, and then introduce CO, control the pressure in the kettle at 0.35MPa, stir and heat up to 120°C, keep warm, keep the pressure, and pump it in after 8 hours Inside the synthesis kettle.

[0026] (2) Carbonylation of acetic anhydride and acetic acid

[0027] 1. The azeotrope is added from the top of the oxo synthesis kettle 1, stirring is started, the rhodium catalyst solution is added, methyl iodide and lithium acetate are added simultaneously, the temperature is raised, the pressure is increased, and CO gas is fed through the gas distributor 8 from the bottom of the kettle simultaneously, The feeding amount is 5-30% (v / w) of the reaction liquid amount. When the reaction starts, open the ...

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Abstract

The invention discloses a method for preparation of acetic anhydride and acetic acid by means of carbonyl synthesis of methyl acetate and methanol azeotrope. The synthesis reaction is operated in a carbonyl synthesizing kettle (1) which is provided with a mixer, a bypass circulation device controlled by a high-pressure pump and a gas distributor (8) at the bottom. The method includes steps of adding azeotrope and catalyst from the upper portion of the kettle, and gaseous carbon monoxide is fed into the kettle from the bottom of the kettle through the gas distributor (8). The internal pressureof the kettle is 3.0-4.5MPa, and the reaction temperature is 140-220 GEG C. The catalyst includes rhodium catalyst, catalysis-supporting methyl iodide and lithium acetate, the rhodium catalyst with the concentration ranging from 200ppm to 800ppm is selected from rhodium triiodide or rhodium chloride, adding quantity of the methyl iodide is 10-30% of that of the azeotrope, and the concentration ofthe lithium acetate is two to three times of that of the rhodium catalyst. Reaction liquid sequentially passes through a flash evaporation kettle (2), a light component removing tower (3), an acetic acid tower (4) and an acetic anhydride tower (5) to obtain acetic anhydride with purity higher than 97% and acetic acid with purity higher than 99%. The method effectively resolves the problem of comprehensive utilization of methyl acetate and methanol azeotrope.

Description

1. Technical field [0001] The invention relates to a method for preparing basic organic chemical raw materials acetic anhydride and acetic acid. To be precise, the by-product methyl acetate and methanol azeotrope in the production of polyvinyl alcohol are used as raw materials, and the carbonylation synchronously generates acetic anhydride and acetic acid and separates them. method. 2. Background technology [0002] The traditional preparation methods of acetic anhydride include the ketene method using acetic acid as raw material, the oxidation method using acetaldehyde as raw material, etc. In recent years, there has been a direct carbonylation method of methyl acetate and CO under the action of a rhodium catalyst. The traditional preparation methods of acetic acid include acetaldehyde oxidation, butane liquid-phase oxidation, methanol high-pressure carbonylation and methanol low-pressure carbonylation, etc. [0003] Polyvinyl alcohol is prepared by reacting polyvinyl acet...

Claims

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Application Information

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IPC IPC(8): C07C53/08C07C51/083C07C51/56C07C53/12C07C51/44C07C51/573
Inventor 吴福胜冯加芳季学勇陈俊季学满
Owner ANHUI WANWEI UPDATED HIGH TECH MATERIAL CO LTD
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