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Method for purifying polyoxymethylene dimethyl ether

A technology of dimethyl ether and polyoxymethylene, used in chemical instruments and methods, preparation of organic compounds, organic chemistry, etc.

Active Publication Date: 2019-06-11
CHINA PETROLEUM & CHEM CORP +1
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

[0008] The technical problem to be solved in the present invention is that in the purification process of purifying polyoxymethylene dimethyl ether by rectification, the problem that the material clogs the top of the rectification tower is difficult for long-term continuous production and operation, and a method for purifying polyoxymethylene dimethyl ether is provided , this method overcomes the shortcoming of accumulation at the top of the rectification tower, which is beneficial to the long-term continuous operation of the production

Method used

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  • Method for purifying polyoxymethylene dimethyl ether
  • Method for purifying polyoxymethylene dimethyl ether
  • Method for purifying polyoxymethylene dimethyl ether

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0033]The neutral reaction mixture obtained by the reaction unit is firstly passed through the first rectification tower to remove the first fraction DMM by rectification at 0.1 MPa, a reflux ratio of 1, and a tower bottom temperature of 105°C. The two-phase extractant composed of water and cyclohexane in a ratio of 1:1, enters the extraction tower with the ratio of 2:1 with the liquid in the first tower, and the extracted phase enters the second rectification tower. The operating conditions are 0.08MPa, The reflux ratio is 8, the temperature of the tower bottom is 150°C, the second fraction containing cyclohexane solvent and n=2 polyoxymethylene dimethyl ether is obtained from the top of the tower, and the polyoxymethylene dimethyl ether containing n=3-8 is obtained from the tower bottom The second tower still liquid. The second fraction enters the solvent recovery tower, and is rectified under the conditions of normal pressure, reflux ratio of 2, and tower bottom temperature...

Embodiment 2

[0037] The neutral reaction mixture obtained by the reaction unit is firstly passed through the first rectification tower to remove the first fraction DMM by rectification under the conditions of 0.05MPa, reflux ratio of 3, and tower bottom temperature of 88°C. A two-phase extractant composed of NaOH-containing aqueous solution and n-hexane at a ratio of 0.2:1, enters the extraction tower at a ratio of 1:5 with the bottom liquid of the first tower, and the extracted phase enters the second rectification tower at an operating condition of 0.05 MPa, the reflux ratio is 4, the temperature of the tower bottom is 130 °C, the second fraction containing n-hexane solvent and n=2 polyoxymethylene dimethyl ether is obtained from the top of the tower, and the polyoxymethylene dimethyl ether containing n=3-8 is obtained from the tower bottom The second tower bottom liquid of ether. The second fraction enters the solvent recovery tower and is rectified under the conditions of 0.1MPa, reflu...

Embodiment 3

[0039] Using paraformaldehyde and methylal as raw materials, the reaction mixture obtained after acid catalysis is firstly passed through the first rectification tower to remove the first distillate DMM by rectification at 0.15MPa, reflux ratio of 0.5, and tower bottom temperature of 125°C The two-phase extractant that water and normal heptane form with the ratio of 3:1 enters the extraction and separation pump with the ratio of 4:1 with the first tower bottom liquid, obtains the extraction phase and enters the second rectifying tower, and the operating condition is 0.03MPa , the reflux ratio is 1, the temperature of the tower bottom is 116 ° C, the second fraction containing n-heptane solvent and n=2 polyoxymethylene dimethyl ether is obtained at the top of the tower, and the polyoxymethylene dimethyl ether containing n=3-8 is obtained from the tower bottom The second tower bottom liquid of ether. The second fraction enters the solvent recovery tower and is rectified under th...

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Abstract

The invention adopts a technical scheme comprising the following steps: a reaction mixture is separated at a first fractionating tower to remove a first fraction mainly comprising dimethoxymethanel; first tower bottoms are extracted at an extraction unit by a biphasic extracting agent containing an organic solvent and an aqueous phase, and an extract phase containing polyoxymethylene dimethyl ether (n is equal to 2-8) and the organic solvent is obtained and is an aqueous phase containing formaldehyde; a second fraction containing the organic solvent and polyoxymethylene dimethyl ether (n is equal to 2) and second tower bottoms containing polyoxymethylene dimethyl ether (n is equal to 3-8) are obtained from the extract phase at a second fractionating tower; solvent recovery tower bottoms and a fraction containing high-purity polyoxymethylene dimethyl ether (n is equal to 2) are obtained from the second fraction at a solvent recovery tower bottom; second tower bottoms are fractionated at a third fractionating tower to obtain a product fraction containing polyoxymethylene dimethyl ether (n is equal to 3-5) and third tower bottoms containing polyoxymethylene dimethyl ether high polymer (n is larger than 5).

Description

technical field [0001] The present invention relates to the separation process of polyoxymethylene dimethyl ether, especially relates to the preparation of polyoxymethylene dimethyl ether with high purity n=3-5 from the reaction mixture containing polyoxymethylene dimethyl ether obtained in the reaction of paraformaldehyde as raw material ether method. Background technique [0002] With the sharp increase of energy consumption in modern society, the increasing shortage of petroleum resources, and the increasing pressure on the environment, it is urgent to develop new clean diesel fuels. The use of oxygen-containing compounds as diesel additives is a convenient and effective measure without adding additional devices or changing the engine structure, and has become a new idea for the development of the petroleum industry. [0003] Polyoxymethylene dimethyl ether (PODE) is an oxygen-containing compound with the general formula: CH 3 O(CH 2 O)nCH 3 , where n is an integer &g...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): C07C43/30C07C41/58
CPCC07C41/58C07C43/30
Inventor 顾军民裴义霞赵精彩
Owner CHINA PETROLEUM & CHEM CORP
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