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Purification method for polyoxymethylene dimethyl ether(PODE)

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

Active Publication Date: 2017-04-26
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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  • Purification method for polyoxymethylene dimethyl ether(PODE)
  • Purification method for polyoxymethylene dimethyl ether(PODE)
  • Purification method for polyoxymethylene dimethyl ether(PODE)

Examples

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Effect test

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 first tower bottom is mixed with water at a ratio of 1:0.25 and then enters the second rectification tower for rectification under the conditions of 0.02MPa, reflux ratio of 5, and tower bottom temperature of 101°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 unit for recycling. The ...

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. Distill at 0.1MPa, reflux ra...

Embodiment 3

[0041] Using paraformaldehyde and methylal as raw materials, the reaction mixture obtained after catalysis and deacidification is firstly rectified by the first rectification tower at 0.15MPa, reflux ratio of 0.5, and tower bottom temperature of 126°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 a top temperature of 105°C, re...

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Abstract

The invention needs to solve a technical problem of being hard to operate continuously in long-term when materials block an overhead of rectifying column in the process of purifying the PODE by distillation. An adopted technical scheme includes following steps: (a) a reaction mixture, produced through a reactive synthesis unit, enters into a first rectifying column. A first fraction, mainly including Methylal, is separated and a first column residue is produced; (b) the first column residue and make-up water enter into a second rectifying column, and a second column residue and a second overhead of rectifying column light ends including PODE2 raw material are produced by separation; (c) after adding extraction agent in the second overhead of rectifying column light ends, raffinate is separated and extract phase is produced; (d) a second column residue enters into a fourth rectifying column. Production fraction containing PODE 3-5 is separated by the overhead of rectifying column.

Description

technical field [0001] The invention relates to a method for purifying polyoxymethylene dimethyl ether, in particular to preparing high-purity PODE from a reaction mixture containing polyoxymethylene dimethyl ether obtained from a reaction in which paraformaldehyde is a raw material 3～5 Methods. 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 less than 10, and for PODEs with...

Claims

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Application Information

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IPC IPC(8): C07C41/58C07C43/30
CPCC07C41/58C07C43/30
Inventor 裴义霞顾军民吕国强
Owner CHINA PETROLEUM & CHEM CORP
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