Method for separating dimethyl carbonate and methanol azeotrope

A technology of dimethyl carbonate and azeotrope, which is applied in the field of steam permeation membrane separation technology to separate dimethyl carbonate and methanol azeotrope, which can solve the problem of reducing membrane area, large load of methanol recovery tower, large heat load of extraction water, etc. Problems, to achieve the effect of small concentration polarization, improve safety and reliability, and increase operating temperature

Active Publication Date: 2008-03-19
PETROCHINA CO LTD +1
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Problems solved by technology

German patent DE2607003 discloses the method that utilizes the method for pressurized fractionation to make dimethyl carbonate and methanol separation, dimethyl carbonate and methanol mixture (mass ratio is 3: 7) carries out distillation under 1.0MPa nitrogen, tower bottom and tower top The temperature is 150°C and 142°C respectively, and the distillate obtained at the top of the tower after distillation is 95% (wt.) Methanol and 5% (wt.) Dimethyl carbonate, and the bottom of the tower is dimethyl carbonate product, pressurized The distillation method is difficult to operate, requires a large investment in equipment and is less safe
German patent DE 2450856 discloses a low-temperature crystallization method. In this method, the azeotrope should be crystallized at -35°C, and then heated up for secondary distillation, which requires high energy consumption, difficult operation and complicated process.
Japanese patent JP 270249 discloses the use of benzene as an entrainer to separate the azeotrope of dimethyl carbonate and methanol. The operation process is long, there are many control units, and the energy consumption is large. The introduction of the benzene entrainer causes environmental pollution and affects product quality.
U.S. Patent US P3963586 discloses a water extraction rectification. This method uses oil phase reflux, which leads to 1) a large load on the reboiler of the water extraction tower, and 2) a large amount of extracted water corresponding to a unit recovery rate, resulting in a large heat load for the extracted water. Large, the amount of water extracted in

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  • Method for separating dimethyl carbonate and methanol azeotrope

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Embodiment 1

[0023] Take dimethyl carbonate and methanol azeotrope as vapor feed A, dimethyl carbonate content 30% (wt), methanol content 70% (wt), mass flow rate is 25kg / h, feed pressure is 0.4Mpa, enters The temperature of the material is 105°C, and it enters the membrane separator 1 to contact with the GKSS POMS-silicalite / PEI composite membrane. The downstream side of the membrane separator is evacuated with a vacuum pump 3 to maintain the vacuum at 75mmHg absolute pressure. Ester molecules have selective passability, and dimethyl carbonate molecules pass through the membrane preferentially driven by the vapor partial pressure difference on both sides of the membrane, and are enriched on the permeation side of the membrane, and condensed into liquid in the condenser 2 under vacuum and low pressure. The dimethyl carbonate content in the mixture B is 56% (wt) through gas chromatography analysis, and the dimethyl carbonate product can be further purified by conventional rectification to ob...

Embodiment 2

[0025] Take dimethyl carbonate and methanol azeotrope as vapor feed A, dimethyl carbonate content 30% (wt), methanol content 70% (wt), mass flow rate is 25kg / h, feed pressure is 0.1Mpa, enters The material temperature is 64°C, and it enters the membrane separator 1 to contact with the GKSS POMS / PEI composite membrane. The downstream side of the membrane separator is evacuated with a vacuum pump 3 to maintain a vacuum degree of 25mmHg absolute pressure, and the separation membrane is effective against the dimethyl carbonate molecules in the raw material. With selective passability, dimethyl carbonate molecules pass through the membrane preferentially driven by the difference in vapor partial pressure on both sides of the membrane, and are enriched on the permeate side of the membrane, and are condensed into liquid in the condenser 2 under vacuum and low pressure. The liquid mixture B The middle dimethyl carbonate content is 40.5% (wt) through gas chromatographic analysis, across...

Embodiment 3

[0027] Take dimethyl carbonate and methanol azeotrope as steam feed A, dimethyl carbonate content 25% (wt), methanol content 75% (wt), mass flow is 25kg / h, feed pressure is 0.4Mpa, enters The temperature of the material is 105°C, it enters the membrane separator 1 and contacts with GKSSPOMS / PEI, and the downstream side of the membrane separator is evacuated with a vacuum pump 3 to maintain the vacuum at 10mmHg absolute pressure, and the separation membrane selectively passes through the dimethyl carbonate molecules in the raw material Dimethyl carbonate molecules preferentially pass through the membrane driven by the vapor partial pressure difference on both sides of the membrane, enrich on the permeate side of the membrane, and condense into liquid in condenser 2 under vacuum and low pressure. Dimethyl carbonate in the liquid mixture B Methyl ester content is 40% (wt) through gas chromatographic analysis, across the azeotropic composition, can be further purified by convention...

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Abstract

The utility model relates to a method which utilizes a vapour permeation membrane to separate dimethyl carbonate from methanol azeotrope. Saturated vapour at the temperature of 64 to 120 DEG C and with the pressure of 0.10 to 0.6 MPa is sent into a membrane separator and is contacted with a separation membrane, the downstream side of the membrane separator keeps the vacuum degree at 4 to 200 mmHg by vacuum pumping, the dimethyl carbonate first passes through a concentration membrance filter at the permeation side of the membrane and is condensed into liquid under the condition of vacuum and low pressure, the liquid mixture directly enters into an atmospheric rectifying column, dimethyl carbonate with more than or equal to ninety nine point five percent of content is produced from the bottom of the column, and high-concentration methanol is produced from the interception side of the membrane separator and enters into next technique unit. The separation membrane is an organic composite membrane, an organic and mineral composite membrane or a mineral membrane which can preferentially permeate dimethyl carbonate, and the method has the advantages of simple technique and low energy consumption; the throughput of the permeation of the membrane is increased, and the area of the membrane is reduced; safety and reliability are increased, and the purity of dimethyl carbonate is increased as well.

Description

Technical field: [0001] The invention relates to a method for separating dimethyl carbonate (abbreviated as DMC) and methanol azeotrope by using steam permeation membrane separation technology. Background technique: [0002] Dimethyl carbonate (DMC) is an environmentally friendly organic chemical raw material, used as carbonylation, carbonyl methoxylation and methylation reagents to replace traditionally used phosgene, methyl chloroformate, and methyl chloride. In addition, dimethyl carbonate has excellent solubility, not only has good compatibility with other solvents, but also has the characteristics of high evaporation temperature and fast evaporation speed, and can be used as a low-toxicity solvent for coatings and pharmaceutical industries. It is used as the electrode solution component of anhydrous lithium battery. The oxygen content in the dimethyl carbonate molecule is as high as 53, which can increase the octane number, increase the oxygen content of gasoline, impr...

Claims

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Application Information

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IPC IPC(8): C07C31/04C07C29/74C07C69/96C07C68/08B01D61/36
Inventor 赵宝泉蒙军康元熙杨吉红张元红
Owner PETROCHINA CO LTD
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