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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

AI Technical Summary

Problems solved by technology

[0008] The technical problem to be solved in the present invention is the problem that in the purification process of purifying polyoxymethylene dimethyl ether by rectification, the material clogs the top of the rectification tower and makes it difficult to operate continuously for a long time. A method for refining polyoxymethylene dimethyl ether is provided , this method overcomes the shortcoming of accumulation at the top of the rectification tower, and is conducive 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

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Embodiment 1

[0034] Using paraformaldehyde and methylal as raw materials, the reaction mixture obtained after catalysis and deacidification is firstly rectified by the first rectification tower at 0.1MPa, reflux ratio is 1, and the tower bottom temperature is 105°C to remove the first fraction. , to obtain the first tower bottom liquid. The liquid in the bottom of the first tower is mixed with water at a ratio of 1:0.2 and then enters the second rectification tower for rectification under the conditions of 0.02MPa, a reflux ratio of 5, and a temperature of the bottom of the tower at 100°C. The top fraction of the second rectification tower and the extractant cyclohexane enter the extraction tower at a ratio of 1:0.5, and the obtained extract phase enters the third rectification tower. Distill at 0.1MPa, reflux ratio of 1, and tower top temperature of 70°C, separate the distillate containing cyclohexane from the top of the third rectification tower, and return it directly to the extraction ...

Embodiment 2

[0039] [Example 2] Using paraformaldehyde and methylal as raw materials, the reaction mixture obtained after catalysis and deacidification is firstly purified by the first rectification tower at 0.05MPa, the reflux ratio is 3, and the temperature of the tower is 88°C. The first fraction was removed by distillation to obtain the first bottom liquid. The first tower still liquid enters the second rectifying tower from the position in the tower, and water is added from the top of the second rectifying tower by 0.05 times consumption of the first tower still liquid, and the operating pressure of the second rectifying tower is 0.04MPa, The reflux ratio is 3, and the rectification is carried out under the conditions of the tower bottom temperature of 120°C. The top fraction of the second rectification tower and the extraction agent n-hexane enter the extraction tower at a ratio of 1:2, and the obtained extract phase enters the third rectification tower. At 0.1MPa, the reflux ratio ...

Embodiment 3

[0041] The reaction mixture obtained after catalysis and deacidification with paraformaldehyde and methylal as raw materials is firstly rectified by the first rectification tower at 0.15MPa, reflux ratio of 0.5, and tower bottom temperature of 125°C to remove the first fraction , to obtain the first tower bottom liquid. The bottom liquid of the first tower enters the second rectification tower from the middle position of the tower, and water is added into the second rectification tower from the top of the second rectification tower in the form of water vapor in an amount of 1:1. The ratio is 2, and the rectification is carried out under the condition that the temperature of the tower bottom is 126°C. The top fraction of the second rectification tower and the extractant n-octane enter the extraction centrifuge at a ratio of 1:4, and the obtained extract phase enters the third rectification tower. At normal pressure, with a reflux ratio of 5 and rectification at a tower top tem...

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Abstract

The technical problem to be solved by the invention is that materials block the tower top of a rectification tower in the process of using rectification to purify polyoxyethene dimethyl ether, which is harder than the problem of long term continuous operation. The adopted technical scheme includes the following steps: (a) reactant mixtures obtained in a reaction synthesis unit firstly enter a first rectification tower; a first fraction including methylal is separated and removed, and a first tower bottoms; (b) The first tower bottoms and makeup water enter into a second rectification tower, and a second tower bottoms and a second tower top light fraction including n=2 polyoxyethene dimethyl ether materials are separated and gained; (c) after adding an extractant, the second tower top light fraction separates a raffinate phase and gains an extraction phase; the extraction phase enter into a third rectification tower; the extractant is recycled and n=2 polyoxyethene dimethyl ether fraction is gained; (d) a second tower bottoms enters into a forth rectification tower; production fraction including n=3-4 polyoxyethene dimethyl ether is separated by the tower top.

Description

technical field [0001] The invention relates to a method for purifying polyoxymethylene dimethyl ether, in particular to preparing high-purity n=3-4 polyoxymethylene dimethyl ether from the reaction mixture containing polyoxymethylene dimethyl ether obtained in the reaction of paraformaldehyde as a 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 ≥ 1 (generally the value is le...

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 裴义霞顾军民张斌
Owner CHINA PETROLEUM & CHEM CORP
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