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Ionic liquid extractive distillation method for separating acetic acid and water

The technology of ionic liquid and separation method is applied in the field of extractive distillation method to separate acetic acid aqueous solution, which can solve the problems of secondary environmental pollution, large solvent loss, disproportionation, etc., and achieves the effect of high safety index and simplified process and operation.

Inactive Publication Date: 2015-02-11
ZHEJIANG UNIVERSITY OF SCIENCE AND TECHNOLOGY
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0004] Problems existing in traditional organic solvents: 1) a large amount of traditional organic solvents are used as extraction agents in the separation process, which will cause serious secondary pollution to the environment; Distillation method and water separation, complex process, high energy consumption; 3) The thermal stability and chemical stability of organic solvents are poor, and side reactions such as decomposition and disproportionation are prone to occur, and the solvent loss is large
However, these studies are almost all about alcohol / water azeotropic systems containing ionic liquids, however, there are few reports on the low relative volatility and near-boiling point systems of acetic acid+water

Method used

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  • Ionic liquid extractive distillation method for separating acetic acid and water
  • Ionic liquid extractive distillation method for separating acetic acid and water
  • Ionic liquid extractive distillation method for separating acetic acid and water

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Effect test

Embodiment 1

[0017] The improved Rose vapor-liquid balance kettle is used to measure the equal-pressure vapor-liquid balance data, the pressure is controlled by a two-stage pressure precision controller, the pressure fluctuation range is (±0.03) kPa, and the balance temperature is measured by a calibrated precision mercury thermometer (accuracy 0.1K). . At 101.32kPa, 1-ethyl-3-methylimidazolium diethyl phosphate ([EMIM][DEP]) was added to aqueous acetic acid (x 水 =0.9), its addition is difficult to separate point (x 水 =0.9) relative volatility α 12 The impact, see Table 1:

[0018] Table 1

[0019]

[0020] It can be seen from Table 1 that the ionic liquid [EMIM][DEP] has a significant salting-out effect, has a high affinity to the acetic acid component, and has a relative volatility from 1.60 (no ionic liquid) to 5.28 (about 50% of the ionic liquid mass content), which is no 3.3 times that of the ionic liquid system, relative volatility α 12 Much higher than the ionic liquid-free ...

Embodiment 2

[0022] Adopt the measurement data of the Rose vapor-liquid balance kettle in the embodiment 1, control the pressure with the secondary pressure precision controller, under 101.32kPa, add the ionic liquid [EMIM][DEP] in the acetic acid aqueous solution, investigate its addition to the component Boiling point difference ΔT b The impact, see Table 2:

[0023] Table 2

[0024]

[0025] It can be seen from Table 2 that with the increase of the content of ionic liquid [EMIM][DEP], the boiling point difference of water+acetic acid system increases from 17.88K (without ionic liquid) to 42.41K (about 50% of the mass content of ionic liquid), indicating that the acetic acid aqueous solution Distillation separation becomes easier.

Embodiment 3

[0027] Adopt the Rose vapor-liquid equilibrium kettle measurement data among the embodiment 1, under 101.32kPa, 1-butyl-3-methylimidazole dibutyl phosphate ([BMIM][DBP]) is added aqueous acetic acid (x 水 =0.9), its addition is difficult to separate point (x 水 =0.9) relative volatility, see Table 3:

[0028] table 3

[0029]

[0030] It can be seen from Table 3 that there is an obvious salting-out effect in ionic liquids, and the relative volatility α 12 Much higher than the ionic liquid-free system, when the mass content of ionic liquid reaches 57.08%, the relative volatility α 12 As high as 9.81, 6.1 times that of the ionic liquid-free system.

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Abstract

The invention discloses an ionic liquid extractive distillation method for separating acetic acid from water. According to the method, a hydrophilic ionic liquid is adopted as an additive, alkyl imidazole cations are adopted as cations, and alkyl phosphate anions or alkyl tetrafluoroboric acid anions are adopted as anions. The mass percentage content of the ionic liquid is 10-80%, and the ionic liquid is a complex of one or two or more ionic liquids. Acetate with a mass percentage content of 0.5-10% is added as an auxiliary agent; the pH value of an acetic acid water solution is regulated, and combination of acid-alkali complexing bonds of the alkaline ionic liquid and acetic acid is enhanced. During separation, light component water is obtained from the top of a rectification tower, and a mixture of the ionic liquid and acetic acid is obtained at a tower kettle; and the ionic liquid in the mixture is recovered through flash evaporation. According to the method, the ionic liquid is adopted as an additive, and the method does not adopt a traditional organic solvent as an extracting agent, such that the method is a green separation method. Also, process flow can be simplified, and energy consumption can be reduced, such that significant economic benefit can be provided.

Description

technical field [0001] The invention relates to the field of separation of acetic acid aqueous solution by extraction and rectification, in particular, hydrophilic ionic liquid is used as an additive for extraction and rectification of acetic acid water. Background technique [0002] Acetic acid is an important organic chemical raw material. As a raw material, solvent or by-product, it widely exists in industries such as basic organic synthesis, medicine, food, dyes, spices and pesticides. A large amount of acetic acid wastewater is produced in these production processes. If it is directly discharged without recycling acetic acid, it will pollute the environment and waste resources. Therefore, it is of great significance to study the separation of acetic acid / water system for environmental protection and resource utilization. At present, there are many separation methods for studying acetic acid aqueous solution at home and abroad, mainly including rectification, extraction...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C07C53/08C07C51/44B01D3/40
CPCB01D3/40B01D2202/20C07C51/44C07C53/08Y02P20/54
Inventor 彭勇
Owner ZHEJIANG UNIVERSITY OF SCIENCE AND TECHNOLOGY
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