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Method for continuously producing dimethyl carbonate and co-producing 1, 2-propylene glycol by virtue of transesterification method

A technology of dimethyl carbonate and propylene glycol is applied in the preparation of carbonate/haloformate, the preparation of organic carbonates, the production of bulk chemicals, etc. Separation and other problems, to achieve the effect of high yield, reduced labor intensity, and less emissions

Inactive Publication Date: 2015-04-29
SHANDONG SHIDA SHENGHUA CHEM GROUP +1
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  • Abstract
  • Description
  • Claims
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Problems solved by technology

[0003] Aiming at the problems in the prior art, the present invention provides a method for the continuous production of dimethyl carbonate and co-production of 1,2-propanediol by transesterification. 2-propanediol is difficult to separate, which leads to the problems of low yield, low purity and non-continuous production of 1,2-propanediol. The 1,2-propanediol produced by the present invention is of good quality and can meet the production requirements of pharmaceutical grade. The operation process is safe, energy-saving, High yield, the discharge of feed liquid in the tower tank is reduced by more than 50%, and continuous production is realized

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  • Method for continuously producing dimethyl carbonate and co-producing 1, 2-propylene glycol by virtue of transesterification method

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Embodiment 1

[0028] Embodiment 1 A method for continuously producing dimethyl carbonate and co-producing 1,2-propanediol by transesterification method, comprising the following steps:

[0029] (1) Reactive distillation: propylene carbonate, methanol and methanol alkali metal catalyst are sent into the mixing tank for mixing, the molar ratio of methanol and propylene carbonate in the mixture is 7:1, and the content of methanol metal catalyst is the total weight of the mixture The reaction temperature of propylene carbonate and methanol in the synthesis tower is 70-75 ℃, the pressure is normal pressure, the reflux ratio is 1.0, and the reaction residence time is 2h;

[0030] (2) recovery of dimethyl carbonate: the methanol and dimethyl carbonate azeotrope at the top of reactive distillation column T1 are sent into pressurized distillation column T4, and pressure distillation is carried out, and the temperature in the tower is 130-140 ° C, The pressure is 0.5-0.6MPa, and the obtained tower st...

Embodiment 2

[0037] Embodiment 2 A method for continuously producing dimethyl carbonate and co-producing 1,2-propanediol by transesterification method, comprising the following steps:

[0038] (1) Reactive distillation: propylene carbonate, methanol and methanol alkali metal catalyst are sent into the mixing tank for mixing, the molar ratio of methanol and propylene carbonate in the mixture is 11:1, and the content of methanol metal catalyst is the total weight of the mixture. The reaction temperature of propylene carbonate and methanol in the synthesis tower is 70-75 ℃, the pressure is normal pressure, the reflux ratio is 3.0, and the reaction residence time is 1h;

[0039] (2) Reclaiming dimethyl carbonate: the methanol and dimethyl carbonate azeotrope at the top of reactive distillation column T1 are sent into pressurized distillation column T4, and pressure distillation is carried out, and the temperature in the tower is 150-170° C., The pressure is 0.6-0.7MPa, and the obtained tower s...

Embodiment 3

[0046] Embodiment 3 A method for continuously producing dimethyl carbonate and co-producing 1,2-propanediol by transesterification method, comprising the following steps:

[0047] (1) Reactive distillation: propylene carbonate, methanol and methanol alkali metal catalyst are sent into the mixing tank for mixing, the molar ratio of methanol and propylene carbonate in the mixture is 9:1, and the content of methanol metal catalyst is the total weight of the mixture. The reaction temperature of propylene carbonate and methanol in the synthesis tower is 70-75 ℃, the pressure is normal pressure, the reflux ratio is 2.0, and the reaction residence time is 1h;

[0048] (2) Reclaiming dimethyl carbonate: the methanol and dimethyl carbonate azeotrope at the top of reactive distillation tower T1 are sent into pressurized distillation tower T4, and pressurized distillation is carried out, and the temperature in the tower is 140-150 ℃, The pressure is 0.6MPa, and the obtained tower still l...

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Abstract

The invention relates to a method for continuously producing dimethyl carbonate and co-producing 1, 2-propylene glycol by virtue of a transesterification method. The method comprises the following steps: (1) reacting and rectifying; (2) recovering dimethyl carbonate; (3) recovering methanol; (4) separating methanol and 1, 2-propylene glycol; (5) carbonizing; (6) filtering; (7) separating 1, 2-propylene glycol; and (8) refining 1, 2-propylene glycol. The method provided by the invention is used for solving the problem in the prior art that 1, 2-propylene glycol is low in yield and low in purity and cannot be continuously produced as a methanol alkaline metal catalyst is hard to be separated from 1, 2-propylene glycol. The purity of 1, 2-propylene glycol produced by the invention reaches 99.99%, so that the pharmaceutical grade production requirement is realized. The method is safe in operating process, energy-saving and high in yield, the discharge of kettle bottom slurry is reduced by 50% or over, and continuous production is realized.

Description

technical field [0001] The invention relates to a method for continuously producing dimethyl carbonate and co-producing 1,2-propanediol by a transesterification method, and belongs to the field of compound synthesis. Background technique [0002] In the prior art, propylene carbonate and methanol are sent into a reaction tower, and transesterification is carried out in the presence of a catalyst, and the azeotrope of dimethyl carbonate (DMC) and methanol is obtained at the top of the reaction tower, and the azeotrope is condensed and then sent to the reaction tower. The DMC and methanol are separated into the pressurized rectification tower, the crude DMC product is obtained from the pressurized rectification tower still, and the high-purity dimethyl carbonate product is obtained after purification. 1,2-Propanediol (PG) is obtained, and the unreacted methanol, propylene carbonate, etc. are recovered and recycled. The catalyst in the existing technology is an alkali metal me...

Claims

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Application Information

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IPC IPC(8): C07C69/96C07C68/06C07C31/20C07C29/128
CPCC07C29/128C07C29/88C07C68/065C07C69/96C07C31/205Y02P20/52
Inventor 丁伟涛于海明郭建军李新胡涛刘强武同霞钱学一王志水
Owner SHANDONG SHIDA SHENGHUA CHEM GROUP
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