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Process for production of acetic acid

A technology of acetic acid and the periodic table of elements, applied in the directions of organic chemistry method, carbon monoxide reaction to prepare carboxylic acid, organic chemistry, etc., to achieve the effects of increasing acetic acid yield, improving catalyst activity, and realizing acetic acid productivity

Inactive Publication Date: 2008-09-24
DAICEL CHEM IND LTD
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

However, introducing hydrogen into the reactor to keep the partial pressure of hydrogen high will lose the effect of reducing by-products, one of the advantages obtained by reducing the concentration of water in the reaction liquid.

Method used

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Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0034] Will contain rhodium complex ([Rh(CO) 2 I 4 ] - ) Catalyst composition liquid (rhodium catalyst concentration: 700 wtppm based on rhodium, solvent: 86 wt% acetic acid, 2 wt% water, 12 wt% lithium iodide) was continuously introduced into a 28.8ml vessel with a heating jacket Wherein, the rhodium complexes are all trivalent rhodium complexes, a mixed gas with a ratio of hydrogen to carbon monoxide of 1:3 is supplied in an amount of 2.3 mol times the amount of hydrogen relative to rhodium, and the catalyst composition liquid and the The mixed gas was contacted for 53 seconds at a pressure of 2.8 MPaG and a temperature described in Table 1. The ratio (%) of monovalent rhodium production measured by infrared absorption spectroscopy is shown in Table 1.

[0035] Table 1

[0036] Contact temperature (℃)

Embodiment 2

[0038] The catalyst composition liquid containing the rhodium complex (the rhodium catalyst concentration: 700 wtppm based on rhodium, solvent: 86 wt% of acetic acid, 2 wt% of water, 12 wt% of lithium iodide) is continuously introduced into a heating jacket In the 28.8ml container, the rhodium complexes are all trivalent rhodium complexes, and the mixed gas with a ratio of hydrogen to carbon monoxide of 1:3 is supplied in an amount of 1.1 mol times that of hydrogen relative to rhodium. The catalyst The composition liquid and the mixed gas are contacted for 53 seconds at a pressure of 2.8 MPaG and a temperature of 125°C. The ratio (%) of monovalent rhodium production measured by infrared absorption spectroscopy was 72%.

Embodiment 3

[0040] In a reactor with an internal volume of 1L, the reaction raw material methanol (0.21kg / h) and carbon monoxide, a catalyst liquid containing rhodium catalyst and lithium iodide, and methyl iodide (0.28kg / h) and methyl acetate (0.095kg) were continuously supplied. / h), low boiling point components of water (0.008kg / h); react at a reaction pressure of 3.0MPa, a hydrogen partial pressure of 29kPa, and a reaction temperature of 196℃; introduce the reaction liquid (water) into the evaporation tank at a flow rate of 2.07kg / h Concentration: 0.45 wt%, methyl acetate concentration: 4.7% by weight, methyl iodide concentration: 14.5 wt%, rhodium catalyst concentration: 930 wt ppm in terms of rhodium, lithium iodide concentration: 11.7% by weight), and low boiling point components are evaporated And the generated acetic acid; the unevaporated catalyst liquid (rhodium catalyst concentration: 1480 ppm by weight calculated as rhodium) is pressurized with a pump and circulated into the reac...

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Abstract

Disclosed is a process for producing acetic acid by reacting methanol with carbon monooxide continuously in the presence of a catalyst of a metal belonging to Group VIII on the periodic table, a salt of an iodide, methyl iodide and water. In the process, the reaction solution is removed continuously and subjected to a distillation step wherein the pressure is lower than that included in the reaction conditions to be separated into a low-boiling component fraction and a high-boiling component fraction containing the metal belonging to Group VIII on the periodic table and the salt of the iodide, and hydrogen is introduced into an region required for returning the separated high-boiling component fraction to the reactor in an amount of 0.1 times by mole larger than that of the metal belonging to Group VIII on the periodic table and is allowed to contact with the high-boiling component fraction at 80 DEG C or higher for at least 6 seconds before the high-boiling fraction returns to the reactor. The process can increase the activity of the catalyst in the reactor without the need of increasing the partial pressure of hydrogen in the reactor to an excess degree, can inhibit a shift reaction to reduce the production of any by-product, and can produce acetic acid in an industrial scale with good efficiency and high productivity rate.

Description

Technical field [0001] The invention relates to a method for preparing acetic acid from methanol and carbon monoxide. Background technique [0002] Acetic acid is one of the basic chemicals. It is an important chemical in the petrochemical industry, polymer chemical industry, organic chemical industry, and pharmaceutical and pesticide manufacturing industries. As a method for preparing acetic acid, there are various methods. Among these methods, the method of preparing acetic acid from methanol and carbon monoxide is the best method in the industry. [0003] As an improvement method of this method, a method of reducing the concentration of water in the reaction liquid has been proposed (Japanese Patent Publication No. 4-69136 and Japanese Patent Publication No. 7-23337). That is, a technique is disclosed that can increase the productivity of acetic acid and reduce the yield of by-products by reducing the water concentration in the reaction liquid. In these technologies, it is als...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C07C51/12C07C53/08C07B61/00
CPCC07C51/12C07C53/08C07B61/00
Inventor 小岛秀隆
Owner DAICEL CHEM IND LTD
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