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Purification method of polyoxymethylene dimethyl ether

A technology of dimethyl ether and purification method, applied in chemical instruments and methods, preparation of organic compounds, organic chemistry, etc., to reduce the possibility of clogging and improve efficiency

Active Publication Date: 2015-03-25
CHINA PETROLEUM & CHEM CORP +1
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0009] The technical problem to be solved in the present invention is the problem of difficulty in long-term continuous production and operation in the purification of polyoxymethylene dimethyl ether purified by rectification. The shortcomings accumulated at the top of the rectification tower are conducive to long-term continuous operation of production

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  • Purification method of polyoxymethylene dimethyl ether

Examples

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Effect test

Embodiment 1

[0033] Using paraformaldehyde and methylal as raw materials, polyoxymethylene dimethyl ether is synthesized by trifluorosulfonic acid catalysis. After the reaction, the pH value of the reaction mixture is adjusted to PH=7.5. The composition of the reaction mixture to be separated was detected as follows: Methanol, 3.9%; Methylal, 40.56%; Paraformaldehyde, 8.5%; n=2, 23.02%; n=3, 12.30%; n=4, 6.31%; n =5, 3.14%; n>5, margin. Under the operating condition of the reflux ratio of 0.5, the distillation tower top temperature is 41°C to remove the first fraction; the first rectification tower is operating at the operating pressure of 0.05Mpa and the reflux ratio of 3 conditions, and the top temperature of 69~71°C is separated. second fraction. The bottom liquid of the second column was cooled to room temperature, and the solid paraformaldehyde was removed through centrifugation; the pressure of the second rectification column was 0.025Mpa, and the reflux ratio was 8, and the third f...

Embodiment 2

[0035] The sulfuric acid catalyzed reaction mixture of methylal and paraformaldehyde consisted of: methanol, 3.3%; methylal, 33.19%; paraformaldehyde, 10.5%; n=2, 25.15%; n=3, 13.44%; n =4, 6.88%; n=5, 3.43%; n>5, margin. After the reaction, the pH value of the reaction mixture was adjusted to pH=7. Under the operating condition that the reflux ratio is 1, the temperature at the top of the distillation column is 43°C to remove the first fraction; the first fraction is separated at the operating pressure of 0.1Mpa and the reflux ratio is 5, and the second fraction with a top temperature of 103°C is separated. fraction. After removing the second fraction, the liquid in the second column was cooled to -10°C, and the solid paraformaldehyde in it was removed by low-temperature suction filtration; the pressure of the second rectification column was 0.005Mpa, and the reflux ratio was 6, and the top of the column was collected The third fraction at a temperature of 70 °C. The analy...

Embodiment 3

[0041] The sulfuric acid catalyzed reaction mixture of methylal and paraformaldehyde consisted of: methanol, 3.3%; methylal, 33.19%; paraformaldehyde, 10.5%; n=2, 25.15%; n=3, 13.44%; n =4, 6.88%; n=5, 3.43%; n>5, margin. After the reaction, the pH value of the reaction mixture was adjusted to pH=6.5. Under the operating condition that the reflux ratio is 3, the temperature at the top of the distillation column is 45°C to remove the first fraction; the first fraction is separated at the operating pressure of 0.06Mpa and the reflux ratio is 1, and the second fraction with a top temperature of 85°C is separated. fraction. After removing the second fraction, the liquid in the second tower was cooled to -20°C, and filtered under low-temperature and reduced pressure to remove the solid paraformaldehyde; the second rectification tower was under the condition of a pressure of 0.05Mpa and a reflux ratio of 4. A third fraction was collected with an overhead temperature of 170°C. The...

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Abstract

The invention relates to a purification method of polyoxymethylene dimethyl ether, which is mainly used for solving the technical problem that when polyoxymethylene dimethyl ether in a reaction mixture is purified by a pure serial connection manner of rectifying towers, paraformaldehyde is attached and accumulated on the top of a rectifying tower to block a return pipe and a discharge pipe to cause shut down for maintenance, and thus long-term and continuous production operation is difficult to achieve. The purification method of polyoxymethylene dimethyl ether provided by the invention mainly comprises: (e) cooling second residue to separate out a paraformaldehyde solid, and performing solid-liquid separation to separate paraformaldehyde and obtain mother liquor; (f) rectifying the mother liquor in a second rectifying tower to obtain a third fraction containing n=3-5 polyoxymethylene dimethyl ether and third tower residue containing the rest high polymer components, the technical scheme is used for well solving the above technical problem, and the purification method can be used in the purification production of polyoxymethylene dimethyl ether.

Description

technical field [0001] The invention relates to a method for purifying polyoxymethylene dimethyl ether, in particular to purifying polyoxymethylene dimethyl ether from a reaction mixture containing polyoxymethylene dimethyl ether obtained by reacting materials including paraformaldehyde and methylal in the presence of an acid catalyst. Formaldehyde dimethyl 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...

Claims

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Application Information

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IPC IPC(8): C07C43/30C07C41/58C07C41/56
CPCC07C41/56C07C41/58C07C43/30
Inventor 裴义霞顾军民韩诚康吕国强
Owner CHINA PETROLEUM & CHEM CORP
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