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Method for inhibiting polymerization of acetaldehyde in polyvinyl alcohol and vinyl acetate production process

A vinyl acetate and polyvinyl alcohol technology, applied in the chemical industry, can solve the problems of easy decomposition, hydrolysis of vinyl acetate, affecting the quality of vinyl acetate, etc., and achieves the effects of good polymerization inhibition effect, reducing acetaldehyde content, and improving the purity of refined acetaldehyde

Active Publication Date: 2014-08-06
HUNAN XIANGWEI
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

These polymerization inhibitors do have a certain effect on the inhibition of acetaldehyde, but there are also shortcomings: for example, Wu Chuanying and others use alkali as a polymerization inhibitor, which will cause the hydrolysis of vinyl acetate in the actual production process to generate acetaldehyde and 2-butene Impurities such as aldehydes enter the vinyl acetate refining system and affect the quality of vinyl acetate; the four ammonium salts proposed by Liu Ruijiang are easy to decompose in the process of acetaldehyde refining, which in turn causes the hydrolysis of vinyl acetate, and the reaction system is introduced due to the decomposition of ammonium salts. new impurities

Method used

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  • Method for inhibiting polymerization of acetaldehyde in polyvinyl alcohol and vinyl acetate production process
  • Method for inhibiting polymerization of acetaldehyde in polyvinyl alcohol and vinyl acetate production process

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0025] Acetaldehyde refining and recovery process: refer to figure 1 As shown in the process flow diagram, the reaction liquid of vinyl acetate 1 containing acetaldehyde enters the dealdehyde tower A, and the vinyl acetate and acetic acid in the tower A of the dealdehyde tower A enter into the vinyl acetate refining tower B to obtain refined vinyl acetate 3, and the top of the dealdehyde tower A The distilled vinyl acetate and acetaldehyde gas 4 enters the partial condenser C, part of the condensate of vinyl acetate and acetaldehyde returns to the dealdehyde tower A, part of the vinyl acetate and acetaldehyde 6 enters the acetaldehyde extraction tower D, and the acetaldehyde extraction tower D The raffinate 8 returns to the dealdehyde tower A, the uncondensed gas 7 containing acetylene and a small amount of acetaldehyde in the upper part of the partial condenser C enters the acetaldehyde washing tower E, and the extract 9 containing a small amount of vinyl acetate in the acetal...

Embodiment 2

[0029] refer to figure 1 The process flow shown is the same as in Example 1, except that the polymerization inhibitor is added twice from the acetaldehyde refining tower G (intermittent 3 hours) to the refining and recovery system, and the mass ratio of acetic acid to sodium acetate is 0.4 : 1, the addition concentration is 2000ppm, and the pH value of the acetaldehyde aqueous solution in the regulation system is 5.6.

[0030] Effect: Before adding inhibitor, the mass percentage of paraldehyde distilled from acetaldehyde refining tower G is 9.77%, the purity of refined acetaldehyde is 90.12%, and the content of other impurities is 0.110%. The purity of refined vinyl acetate distilled from vinyl acetate refining tower B is 98.84%; after adding the polymerization inhibitor, the mass percentage of paraldehyde distilled from acetaldehyde refining tower G is 0.075%, and the purity of refined acetaldehyde is 99.82%. The content of other impurities is 0.105%. The purity of the refi...

Embodiment 3

[0032] refer to figure 1 The shown process flow is the same as in Example 1, except that the polymerization inhibitor is added in twice from the raw material tank F of the acetaldehyde refining tower (intermittent 3 hours) to the refining and recovery system, and the mass ratio of acetic acid to sodium acetate is 0.1:1, the added concentration is 25ppm, and the pH value of the acetaldehyde aqueous solution in the adjustment system is 4.8.

[0033] Effect: Before adding inhibitor, the mass percentage of paraldehyde distilled from acetaldehyde refining tower G is 20.77%, the purity of refined acetaldehyde is 78.78%, and the content of other impurities is 0.450%. The purity of refined vinyl acetate distilled from vinyl acetate refining tower B is 98.53%; after adding the polymerization inhibitor, the mass percentage of paraldehyde distilled from acetaldehyde refining tower G is 0.077%, and the purity of refined acetaldehyde is 99.61%. The content of other impurities is 0.313%. ...

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Abstract

The invention belongs to the field of chemical industry and provides a method for inhibiting the polymerization of acetaldehyde in the production process of polyvinyl alcohol and vinyl acetate. The method is to add a polymerization inhibitor to prevent the self-polymerization of acetaldehyde in the process of acetaldehyde refining and recycling, and adjust the pH value of the acetaldehyde aqueous solution in the range of 4.5 to 5.6 in the process of acetaldehyde refining and recycling; The agent is a mixture of acetic acid and sodium acetate, wherein the mass ratio of acetic acid to sodium acetate is 0.02-0.4:1, and the concentration of the polymerization inhibitor added is 25ppm-2000ppm. The method of the invention has the advantages of good polymerization inhibition effect, low cost, can significantly improve the quality of refined vinyl acetate and the recovery rate of acetaldehyde, the polymerization inhibitor is not easy to decompose, and has stable properties and the like.

Description

technical field [0001] The invention belongs to the field of chemical industry and relates to a method for inhibiting the polymerization of acetaldehyde in the production process of polyvinyl alcohol (PVA) and vinyl acetate (VAc). The invention also relates to a method for inhibiting polymerization of acetaldehyde in production processes such as the synthesis and refinement of vinyl acetate, the refinement and recovery of acetaldehyde, and the recovery and utilization of sodium acetate in the production of polyvinyl alcohol. Background technique [0002] In the production process of polyvinyl alcohol (PVA) and vinyl acetate (VAc), the technological process of acetaldehyde purification and recovery is as follows: figure 1 Shown: the reaction liquid of vinyl acetate 1 containing acetaldehyde enters the dealdehyde tower A, the vinyl acetate and acetic acid 2 in the tower of dealdehyde tower A enter the vinyl acetate refining tower B to obtain refined vinyl acetate 3, and the di...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): C07C47/06C07C45/90
Inventor 刘振辉朱泽礼舒晓艳唐松乔刘永杰周金华向龙刚张艳君张耕
Owner HUNAN XIANGWEI
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