Synthetic method of ionic liquid catalyzed propylene carbonate to synthesize dimethyl carbonate

Abstract

The invention relates to a synthetic method of diphenyl carbonate from propylene carbonate by catalysis of an ionic liquid. The method comprises steps of reaction rectification, separation and purification of dimethyl carbonate, and separation and purification of propylene glycol. Methanol, propylene carbonate and an ionic liquid catalyst react in a reactive rectifying tower, and the reaction products are separated; dimethyl carbonate and methanol azeotrope is distilled from the tower top, and, a mixture of propylene glycol, methanol, the catalyst and a small amount of dimethyl carbonate is obtained in the tower kettle; separation of the methanol and methyl carbonate azeotrope from the tower top is achieved by a dimethyl carbonate pressurized rectification tower, a dimethyl carbonate atmospheric rectification and a dimethyl carbonate product tower; separation and purification of propylene glycol in the tower kettle is achieved by a lightness-removing tower, a propylene glycol product tower and a methanol recovery tower; and the separated catalyst returns to the reaction rectifying system for reuse. The usage of the ionic liquid catalyst simplifies the process for dimethyl carbonate synthesis from propylene carbonate and methanol and combined production of propylene glycol, and the method has the advantages of low energy consumption, catalyst reuse and good combined production effect.

Description

technical field [0001] The invention relates to a synthesis method for synthesizing dimethyl carbonate and co-producing propylene glycol through transesterification reaction of propylene carbonate and methanol through ionic liquid catalysis. Background technique [0002] The production methods of dimethyl carbonate (DMC) include transesterification of methanol and propylene carbonate (PC), carbonyl oxidation of methanol and carbon monoxide, alcoholysis of methanol and urea, etc. At present in my country, the industrialized production method of dimethyl carbonate is mainly to produce dimethyl carbonate by transesterification reaction of propylene carbonate and methanol under the effect of catalyst sodium methoxide, and co-produce propylene glycol (PG) simultaneously. [0003] The transesterification reaction of propylene carbonate and methanol is an equilibrium reaction, and the reaction equilibrium constant is relatively small. In order to break the reaction balance and con...

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Problems solved by technology

In the subsequent rectification process, with the evaporation of volatile components, solid particles will also crystallize out of the solution, which will cause fouling of the reboiler of the rectification column or solid matter attached to the filler, affecting Continuous and normal operation of the equipment, for this reason the patent CN202717726U specially proposes an anti-dirty clogging tray to solve this problem

[0006] As can be seen from the above patents, the use of sodium methylate catalysts makes the existing dimethyl carbonate synthesis process very complicated, and there are many other disadvantages, such as a large amount of catalyst, a large amount of solid waste residues are produced after the catalyst fails, Cause environmental pollution, the precipitation of solids in the catalytic system affects the stability of the continuous production of the system, the catalyst cannot be reused, and when the catalyst waste residue is discharged, it will inevitably entrain propylene glycol, resulting in a decrease in the yield of propylene glycol

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