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Method for removing dihydric alcohol or polyol impurities in glycol and increasing yield of glycol

A technology of ethylene glycol and polyols, applied in chemical instruments and methods, bulk chemical production, and preparation of organic compounds, etc., can solve problems such as high energy consumption of rectification, no involvement, multiple separation devices, etc., and reduce construction Effects of investment, process energy saving, and process simplification

Active Publication Date: 2017-06-20
DALIAN INST OF CHEM PHYSICS CHINESE ACAD OF SCI
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

However, regardless of the biomass-based ethylene glycol production process or coal-based ethylene glycol production process, due to the limited selectivity of the catalyst, the reaction system will generate 1,2-propanediol, 1,2-butanediol, 1,2-pentanediol by-products such as diol
Among them, the difference between the boiling points of 1,2-butanediol and ethylene glycol is only 5°C, and the difference between the boiling points of 1,2-pentanediol and ethylene glycol is only 8°C. It is difficult to ensure higher ethylene glycol by ordinary distillation. The efficient removal of 1,2-butanediol is achieved under the premise of high yield, which is also one of the important reasons restricting the industrialization of biomass-based and coal-based ethylene glycol production routes
In addition, diols such as 1,2-propanediol, 1,2-butanediol, 2,3-butanediol, and 1,2-pentanediol have very close boiling points to ethylene glycol, although they can be purified by conventional distillation Separation of 1,2-propanediol, 1,2-butanediol, 1,2-pentanediol and other impurities, but the energy consumption of rectification is high, the cost of heat source steam and the cost of vacuum system are high
[0004] Application No. is 2014107141706 although the invention scheme of 2014107141706 has successfully removed 1,2-propanediol and 1,2-butanediol in ethylene glycol, but the yield of main product ethylene glycol is low (below 70%), has affected ethylene glycol The improvement of diol output is difficult to meet the demand of polyester industry for ethylene glycol; in addition, there are many by-products in this process, which requires more separation devices, which increases fixed investment and total energy consumption, and this invention does not involve 1,2 -Removal of pentanediol

Method used

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  • Method for removing dihydric alcohol or polyol impurities in glycol and increasing yield of glycol
  • Method for removing dihydric alcohol or polyol impurities in glycol and increasing yield of glycol

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0027] Such as figure 1 As shown, under normal pressure, 100 grams of ethylene glycol crude product containing 15% of 1,2-propanediol and 5% of 1,2-butanediol are added to the dehydration reactor, and 2 grams of silicon-aluminum ratio are added. 25 HZSM-5 acid molecular sieve catalyst, heated to 180°C, and reacted for 4 hours. The crude product undergoes dehydration reaction to generate light products such as propionaldehyde, propionaldehyde ethylene glycol acetal, butyraldehyde ethylene glycol acetal, propionaldehyde propylene glycol acetal, 1,4-dioxane, etc. These low boiling point products are all evaporated and mixed with Ethylene glycol separation. The ethylene glycol intermediate in the reactor was sent to the secondary reactor for secondary deep dehydration. The catalyst was 3 grams of HZSM-5 acid molecular sieve with a silicon-aluminum ratio of 80. The reaction temperature was 184°C and the reaction was performed for 2 hours. Secondary deep dehydration completely rem...

Embodiment 2

[0031] Such as figure 1 As shown, under normal pressure, 100 grams of ethylene glycol crude product containing 10% of 2,3-butanediol and 5% of 1,2-pentanediol was added to the dehydration reactor, and 3 grams of silicon The Hβ acid molecular sieve catalyst with an aluminum ratio of 50 was heated to 180°C and reacted for 4 hours. The crude product undergoes dehydration reaction to produce light products such as butanone, butanone glycol ketal, valeraldehyde, pentanone, valeraldehyde glycol acetal, 1,4-dioxane, etc. These low-boiling point products are all evaporated when heated And separated from ethylene glycol. The ethylene glycol intermediate in the reactor is sent to the secondary reactor for secondary deep dehydration. The catalyst is 4 grams of Hβ acid molecular sieve with a silicon-aluminum ratio of 160, and the reaction temperature is 185°C for 2 hours. Secondary deep dehydration completely removes 2,3-butanediol and 1,2-pentanediol. The liquid phase product of the s...

Embodiment 3

[0035] Such as figure 1 As shown, under normal pressure, the crude product of ethylene glycol containing 5% 1,2-butanediol and 1% glycerol is added to a dehydration reaction with a volume of 8 cubic meters at a flow rate of 1 ton / hour Add 100 kg of HZSM-5 acid molecular sieve catalyst with a silicon-aluminum ratio of 80 to the reactor. The reactor is a fully mixed flow reactor with a stirring rate of 280 rpm and a reaction temperature of 182°C. The crude product undergoes dehydration reaction to produce light products such as butyraldehyde glycol acetal, a small amount of butyraldehyde, 1,4-dioxane, hydroxyacetone, and a small amount of acrolein. These low-boiling point products are all evaporated by heating and separated from ethylene glycol. The ethylene glycol intermediate product discharged from the dehydration reactor is sent to the secondary reactor for secondary deep dehydration. The secondary reactor is a tubular reactor with an inner diameter of 0.3 meters and a lengt...

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Abstract

The invention discloses a method for removing dihydric alcohol or polyol impurities in glycol and increasing the yield of glycol. According to the method, glycol containing dihydric alcohols or heteropolyols (such as 1,2-butanediol) is used as a raw material; under the action of a protonic acid catalyst, dihydric alcohols or heteropolyols undergoes a dehydration reaction, a secondary in-depth dehydration reaction, an acetalation reaction; and heteroalcohols are totally converted into low-boiling-point products which are separated through distillation and condensation. Acetal in the low-boiling-point products is subjected to a hydrolysis reaction so as to produce glycol, trace heteroalcohols and aldehydes; and glycol and heteroalcohols are separated through simple distillation and returned to an in-depth dehydration reaction vessel, so the yield of glycol is increased. Meanwhile, the trace heteroalcohols are further converted in the in-depth dehydration reaction vessel; a crude glycol product having undergone two-step dehydration does not contain dihydric alcohol or polyol impurities; and since rectification for separation of the dihydric alcohol or polyol impurities with boiling points close to the boiling point of glycol is not needed, the number of rectifying towers in the whole separation flow and energy consumption are substantially reduced.

Description

technical field [0001] The invention relates to a method for removing dihydric alcohol or polyhydric alcohol impurities in ethylene glycol and increasing the production of ethylene glycol, belonging to the technical field of chemical separation. Background technique [0002] Ethylene glycol is a colorless, odorless, sweet liquid chemical raw material, mainly used to produce polyester materials (used in mineral water bottles, textile raw materials), solvents, antifreeze agents, plasticizers, hygroscopic agents, etc. Among them, the ethylene glycol consumed by the polyester industry accounts for more than 90% of the total consumption, and the mass fraction of ethylene glycol raw materials required for polyester must reach more than 99%. Although my country's ethylene glycol production capacity and output have grown rapidly, it still cannot meet the growing market demand for domestic polyester. The huge market gap has led to an upsurge in the construction of ethylene glycol pla...

Claims

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Application Information

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IPC IPC(8): C07C29/74C07C29/94C07C31/20
CPCC07C29/74C07C29/94C07C31/202Y02P20/52
Inventor 郑明远艾硕张涛王爱琴王晓东
Owner DALIAN INST OF CHEM PHYSICS CHINESE ACAD OF SCI
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