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Refining method of polyoxymethylene dimethyl ether

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

Active Publication Date: 2019-08-06
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 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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  • Refining method of polyoxymethylene dimethyl ether
  • Refining method of polyoxymethylene dimethyl ether
  • Refining method of polyoxymethylene dimethyl ether

Examples

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Comparison scheme
Effect test

Embodiment 1

[0031] 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 0.1MPa, reflux ratio of 1, and tower bottom temperature of 105°C The two-phase extractant that water and hexanaphthene are formed in the ratio of 1:1 enters the extraction tower with the ratio of 2:1 with the first tower still liquid, obtains the extraction phase and enters the second rectifying tower, at normal pressure, reflux Rectification under the condition that the ratio is 2, the top of the tower obtains the second fraction mainly comprising cyclohexane solvent, which is returned to the two-phase extractant; the second tower still liquid containing the polyoxymethylene dimethyl ether of n=2-8 Enter the third rectification tower and the fourth rectification tower rectification under vacuum, obtain the polyoxymethylene dimethyl ether of n=2 and the polyo...

Embodiment 2

[0035] 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 0.05MPa, reflux ratio of 3, and tower bottom temperature of 88°C. ; The aqueous solution containing NaOH and normal hexane form the two-phase extractant with the ratio of 0.2:1, enter the extraction tower with the ratio of 1:5 with the first tower bottom liquid, obtain the extraction phase and enter the second rectifying tower, at 0.1MPa , rectification under the condition that the reflux ratio is 5, and the second fraction mainly comprising n-hexane solvent is obtained at the top of the tower, which is returned in the two-phase extractant; the second tower bottom liquid comprising the polyoxymethylene dimethyl ether of n=2-8 Enter the third rectification tower and the fourth rectification tower vacuum rectification successively, obtain the polyoxymethylene d...

Embodiment 3

[0037] 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 n-heptane are formed with the ratio of 3:1 enters the extraction separation pump with the ratio of 4:1 with the first tower still liquid, obtains the extraction phase and enters the second rectifying tower, at 0.05MPa, reflux Ratio is rectification under the condition of 8, the tower top obtains the second cut that mainly comprises n-heptane solvent, returns in the two-phase extractant; Enter the third rectification tower and the fourth rectification tower rectification under vacuum, obtain the polyoxymethylene dimethyl ether of n=2 and the polyoxymethylene dimethyl ether product of n=3-4 respectively by the tower top, wherein the third The operating c...

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Abstract

The invention solves the technical problem that it is difficult to make a long-term and continuous production and operation in the process of refining polyoxymethylene dimethyl ether through a distillation because the materials and supplies block the top of a distillation tower. The refinement method for polyoxymethylene dimethyl ether utilizes the technical plans which comprise the following steps: (a) a reaction mixture obtained through a reaction synthesis unit firstly enters into a first distillation tower to separate and remove a first fraction which mainly contains methylal to get first tower bottoms; (b) the first tower bottoms enters into an extraction unit to make an extraction with two-phase extraction agents which contain an organic solvent and an aqueous phase to get an extraction phase which contains n=2-8 polyoxymethylene dimethyl ether and the organic solvent, and the extraction phase is the aqueous phase which contains formaldehyde; (c) the extraction phase successively enters into a second distillation tower, a third distillation tower and a fourth distillation tower to respectively get a second fraction which contains the organic solvent, a third fraction which contains n=2 polyoxymethylene dimethyl ether of high purity and a fourth fraction which contains n=3-4 polyoxymethylene dimethyl ether.

Description

technical field [0001] The invention relates to a process for purifying polyoxymethylene dimethyl ether, in particular to preparing high-purity n=3-4 polyoxymethylene dimethyl ether from a reaction mixture containing polyoxymethylene dimethyl ether obtained in the reaction of paraformaldehyde as a raw material base 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 i...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): C07C41/58C07C41/56C07C43/30
CPCC07C41/56C07C41/58C07C43/30
Inventor 裴义霞顾军民张斌赵精彩
Owner CHINA PETROLEUM & CHEM CORP
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