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Method for removing impurities in recycled acetic acid

A technology for acetic acid and impurities, applied in the fields of chemistry and chemical engineering, which can solve the problems of increased energy consumption of the production system, high maintenance frequency of reaction equipment and systems, increased production costs and maintenance costs, etc. The effect of decreasing

Pending Publication Date: 2022-01-25
NANTONG CELLULOSE FIBERS CO LTD +2
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

However, it has been found in the production process for many years that the reaction equipment and system maintenance frequency in the acetic acid recovery process is relatively high, which not only increases the production cost and maintenance cost, but also greatly increases the energy consumption of the production system

Method used

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  • Method for removing impurities in recycled acetic acid

Examples

Experimental program
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Effect test

Embodiment 1

[0042] Take 100kg of acid recovered from cellulose acetate production (concentration is about 30%, about 70% is water), add 1kg of concentrated sulfuric acid (above 98%), and stir the system at 50 degrees for 4h, then add 1.45kg of magnesium acetate to neutralize sulfuric acid to form Magnesium acetate, the reaction was completed after about 0.2h. After the reaction, the degree of substitution of soluble cellulose diacetate, cellulose triacetate, unreacted complete cellulose DS and degree of polymerization DP decreased significantly in acetic acid, and there were soluble cellulose diacetate, cellulose triacetate, unreacted Completely reacted cellulose, the total amount is less than 1%, the main particle size distribution is below 35 μm, about 40% of the particles are below 5 μm, and the haze value of the solution is about 8.7. After the reaction, the hydrophilicity of the impurities is better, and more impurities are dissolved in acetic acid and distributed in water. After th...

Embodiment 2

[0045] Take 100kg of acid recovered from cellulose acetate production (concentration is about 30%, about 70% is water), add 2kg of concentrated sulfuric acid (above 98%), stir the system at 35 degrees for 4h, then add 2.9kg of magnesium acetate to neutralize sulfuric acid to form Magnesium acetate, the reaction was completed after about 0.2h. After the reaction, the degree of substitution of soluble cellulose diacetate, cellulose triacetate, unreacted complete cellulose DS and degree of polymerization DP decreased significantly in acetic acid, and there were soluble cellulose diacetate, cellulose triacetate, unreacted Completely reacted cellulose, the total amount is less than 1%, the main particle size distribution is below 25 μm, about 40% of the particles are below 5 μm, and the haze value of the solution is about 7.6. After the reaction, the hydrophilicity of the impurities is better, and more impurities are dissolved in acetic acid and distributed in water. After the rea...

Embodiment 3

[0048] Take 100kg of recovered acid from cellulose acetate production (the concentration of acetic acid is about 30%, and about 70% is water), add 2kg of concentrated sulfuric acid (above 98%), stir the system at 50 degrees for 4h, and then add 2.9kg of magnesium acetate to neutralize the sulfuric acid Magnesium acetate was formed and the reaction was complete after about 0.2 h. After the reaction, the degree of substitution of soluble cellulose diacetate, cellulose triacetate, unreacted complete cellulose DS and degree of polymerization DP decreased significantly in acetic acid, and there were soluble cellulose diacetate, cellulose triacetate, unreacted Completely reacted cellulose, the total amount is less than 1%, the main particle size distribution is below 20 μm, about 50% of the particles are below 5 μm, and the haze value of the solution is about 1.7. After the reaction, the hydrophilicity of the impurities is better, and more impurities are dissolved in acetic acid and...

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Abstract

The invention belongs to the field of chemistry and chemical engineering, and relates to a method for removing impurities in recycled acetic acid and application thereof. The method for changing the distribution of the polymer in the mixed system comprises the following steps: adding concentrated sulfuric acid into the mixed system for hydrolysis and / or degradation; and adding magnesium acetate or sodium acetate for reaction, then carrying out extraction reaction, and collecting an organic phase to finally obtain pure acetic acid. The method disclosed by the invention is suitable for recycling acetic acid in a mixed system related to cellulose acetate production and removing intermediate products and wastes. The method is simple and easy to operate, no expensive equipment is added, the impurity removal effect is good, the energy consumption and material consumption of the acetic acid recovery process are remarkably reduced, the overhaul frequency of a heat exchanger is reduced, the productivity is improved, and the economic benefit is obvious.

Description

technical field [0001] The invention belongs to the fields of chemistry and chemical industry, and relates to a method for removing impurities in recycled acetic acid and an application thereof. Background technique [0002] Cellulose acetate is usually produced from cellulose-rich cotton linters or wood. After the cellulose is extracted from the raw material, the cellulose is mixed with an acetic acid solution at room temperature and pretreated to obtain a mixture. Acetic anhydride and acetic acid solution are mixed and cooled to obtain a mixed acid, and the mixture and an acidic catalyst are added to the mixed acid to carry out the esterification reaction. During the temperature rise process, the reaction system is continuously vacuumed to flash and volatilize the acetic acid in the reaction system. After the temperature of the reaction system reaches the peak esterification temperature, the vacuum pumping is stopped and the reaction continues until the esterification rea...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C07C51/42C07C51/48C07C51/487C07C53/08C08B3/06
CPCC07C51/42C07C51/48C07C51/487C08B3/06C07C53/08
Inventor 董德俊杨占平徐怡富孙利辉梁银春于星崔磊徐静静周峰陈晓璐高一洲缪书扬
Owner NANTONG CELLULOSE FIBERS CO LTD
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