SU371201A1 - METHOD FOR ISOLATION OF ETHYL ACETATE - Google Patents

Description

one

The invention relates to methods of rectification in the chemical industry, in particular to methods for separating ethyl acetate, and can be used in the production of mbutnlovogo alcohol or n-butyric aldehyde from ethanol, as well as in the separation of products of dry distillation of wood.

A known method for the separation of ethyl acetate from its mixture with acetic acid, methyl ethyl ketone and n-hexane (m.p. 68.7 ° C) is that this mixture is subjected to azeotropic rectification. Isolation of qualitative ethyl acetate from a mixture of reaction by-products obtained in the production of n-butyl alcohol or oil aldehyde and containing 65–70% ethyl acetate, 5–10% water, ethyl alcohol, methyl ethyl ketone and acetic acid is not known by the known method due to the existence of a whole p and azeotropic mixtures (ethyl acetate-water, ethyl alcohol-ethyl acetate, ethyl acetate-methyl ethyl ketone, ethanol-water, methyl ethyl ketone-water, egylacetate-water-ethanol, ethyl acetate-water-methyl ethyl ketop), which boil race the mixture without changing the composition.

The mixture of this composition does not find qualified use and is not disposed of.

In order to obtain ethyl acetate with a high

A step of purity proposes a method for separating ethyl acetate from the fraction of production of α-butyl alcohol or oily aldehyde by treating with methyl alcohol, followed by distilling off the azeotrope with ethyl acetate-methanol and isolating the desired product by azeotropic distillation of methanol. The resulting product contains 98% ethyl acetate.

Studies show that in quality

Azeotropic agent for the separation of ethyl acetate from the mixture can be applied. Methyl alcohol. Methanol does not form an azeotrope with water, ethyl and butyl alcohols and acetic acid, the azeotrope methanol-ethyl acetate contains 44 wt.% Methanol with m.p. 62.3 ° C. (Far below the boiling point of the other components of the mixture and their azeotrons with water, ethanol and ethyl acetate). Methanol forms stratifying azeotropes with hydrocarbons boiling in the range of 60–110 ° C, whereas ethyl acetate does not form azeotropes with them, which allows methanol to be distilled off from a homogeneous azeotrope with ethyl acetate and to produce ethyl acetate. For this

Hydrocarbons C (i and GS) can be used for the purpose, it is preferable to use paraffinic hydrocarbons, for example, n-heptane.

Using the method of azeotropic distillation of the initial mixture with methanol to separate the PII of ethyl acetate from the mixtures as an azeotrope

and azeotropic distillation of the obtained homogeneous azeotrope with hydrocarbons to isolate ethyl acetate from a mixture with methanol allows obtaining commercial ethyl acetate that meets the requirements of GOST 8981-59 for ethyl acetate grade A in a yield of up to 95-97% of potential.

The initial mixture is fed to the distillation column 1, operating under atmospheric pressure, in which 75–80% of the ethylacetate contained in the mixture is fed into the separating agent. The azeotrope methanol-ethyl acetate is removed from the top of the column at a temperature of 62-63 ° C, and the remaining components of the mixture to be separated are from the cube. Azeotrope methanol-ethyl acetate served in a distillation column 2, operating under atmospheric pressure.

A hydrocarbon-removal agent is added to the top of column 2 to remove methanol as an azeotrope. The hydrocarbon feed is calculated based on the loading of the column 2 with methanol and the hydrocarbon content of the azeotrope with methanol.

Commercial ethyl acetate is removed from the bottom of column 2 at a temperature of 77-79 ° C. From the top of column 2 azeotrope methanol-hydrocarbon is taken.

When n-heptane is used as an agent, the temperature of the top of column 2 is 59-60 ° C.

When distilled, distillate is stratified in a settling tank 3 into methanol and hydrocarbon layers. A hydrocarbon layer with a small amount of methanol is fed to the reflux of the column 2. A methanol layer containing a significant amount of hydrocarbon cannot be directly supplied to the PA column, since the presence of the hydrocarbon disrupts the clarity of the separation of ethyl acetate from impurities due to the formation of hydrocarbon-water azeotropes and hydrocarbon alcohols. In view of this, the methanol layer from the settling tank 3 is fed to the distillation column 4, where the dissolved hydrocarbon is distilled off as an azeotrope with methanol, the distillate is fed to the settling tank 3, where it is combined with the distillate of the column 2, and the distillation residue 4 is recovered methanol is fed to the column Y The cycle is fed with methanol.

The ethyl acetate recovery process can also be carried out periodically. In this case, the process is carried out in three stages.

The first stage. The initial mixture and methanol are loaded into the cube of the periodic column, at a temperature of 60-63 C, the azeotrope methanol-ethyl acetate fraction is removed, and the residue is withdrawn from the cube of coloins.

The second stage. The azeotrope methanol-ethyl acetate on the same column is then subjected to distillation with the addition of hydrocarbons.

Distilled azeotrope methanol-hydrocarbon stratified into two layers; the hydrocarbon layer is used to separate the methanol-ethyl acetate azeotrope in the next cycle; the methanol layer is accumulated for regeneration.

Third stage. The methanol is regenerated by distilling the dissolved hydrocarbon from it on the same apparatus, methanol from the bottom of the column is recycled, and the azeotrope of methanol / carbon removed from the azeotrope is added to the distillate after the second stage of the operation.

Example 1. 150 g of a mixture of the following composition,%:

Water10.0

Ethyl acetate 70.0

Methyl ethyl ketone7.0

Ethyl alcohol9.5

n-butyl alcohol2.0

Acetic acid1,5

subjected to periodic distillation with the addition of 80 g of methanol on a column with an efficiency of 15 plates with a reflux ratio of 4. In the range of 61-63 ° C, 182 g of the fraction containing 44% of methanol and 56% of ethyl acetate are taken.

The selected fraction is subjected to distillation with the addition of 75 g of n-heptane, at a temperature of 58-59 0 take 157 g of the methanol-heptane azeotrope, which is layered into two layers: 100 g of the methanol layer with a content of 22.3%

n-heptane and 1.5% ethyl acetate and 57 g of a hydrocarbon layer with a content of 6.5% methanol and 1% ethyl acetate.

In a cube, coloins left 100 g of ethyl acetate with a content of the main substance of 98%.

Example 2. 1000 g / h of a mixture of the composition, according to example 1, is fed to the distillation column 1 with the efficiency of 15 theoretical plates. In the upper part of the column serves 540 g / h of methanol. At a temperature of 62.5 ° C

and reflux number 3 from the column are selected

1239 g / h of distillate containing 44 wt.%

methanol and 56 wt.% distillate and 301 g / h

vat residue.

The distillate of the column 1 is iodized into a distillation column 2 with an efficiency of 15 plates, in the upper part of which 546 g / h of a hydrocarbon layer containing 92.8% heptane and 6, L% metaiol is introduced. At reflux number 2 and top temperature of 59 ° C, 1078 g / h of the methanol-n-heptane azeotrope with a content of 52.8% methanol, 47.1% of n-heptane is taken from column 2. The distillate of column 2 is fed to a sump 3, from which 546 g / h of hydrocarbon layer is returned to column 2, and a methanol layer containing 76.2% of methanol and 22.9% of n-heptane. The methanol layer is fed to the colopne 4, which works without reflux, in which azeotroi and methanol-n-heptane are distilled off at 59 ° C, which is added to the distillate of colony 2.

At steady-state recycling, 1029 g / h of methanol layer is fed from the settling tank 3 to the column 4, from the column 4 it is distilled and iodine to the settling tank 3 484 g / h of the azeotrope methanol-n-heptane. From the cube of column 4, the output is 535 g / hour

methanol recycled to the column.

From the bottom of the column 2, the output 694 g / h of ethyl acetate with a content of 98% of the basic substance. Ethyl acetate recovery rate 97%.

Subject invention

A method of separating ethyl acetate from a mixture containing, in addition to ethyl acetate, acetic acid and methyl ethyl ketone, using azeotropic distillation in the presence of hydrocarbons having a boiling point of 60-110 ° C, characterized in that, in order to increase the purity of the target product, ethyl acetate with 5- 10% water, ethyl alcohol, n-butyl acid, methyl ethyl ketone and acetic acid are treated with methyl alcohol with subsequent distillation of the azestrop ethyl acetate-methanol and isolation of the desired product by azeotropic distillation g .; em a nol a.

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