Process and device for continuously producing glyceryl triacetate

Abstract

The invention discloses a process for continuously producing glyceryl triacetate, which comprises the following steps of: a) introducing a mixture consisting of glycerol, acetic acid, a water-carrying agent and a catalyst into a reactor, and performing esterification reaction at the temperature of between 140 and 170DEG C; and b) introducing a reaction product obtained through the esterification reaction into a dehydrating tower, and performing azeotropic distillation dehydration, wherein the temperature on the top of the dehydrating tower is 85 to 90DEG C. The invention also discloses a device for preparing glyceryl triacetate, which comprises the reactor used for esterification reaction, and the dehydrating tower used for performing azeotropic distillation dehydration on the reaction product in the reactor. The outlet of the reactor is connected with the inlet of the dehydrating tower. In the method, the esterification reaction is divided into two steps, the reaction for generating an intermediate product is mainly performed in the reactor, and the reaction for generating the glycerol triacetate is mainly performed in the dehydrating tower, so that the yield of the glycerol triacetate is improved finally. Experiments prove that the yield of the glyceryl triacetate is 92 to 93 percent through the method provided by the invention.

Description

Technical field [0001] The present invention relates to a preparation method of esters, and in particular to a process and device for the continuous production of triacetin. Background technique [0002] Triacetin, also known as triacetin, English name: glycerol triacetate; its molecular formula is: C 9 H 14 O 6 , soluble in alcohol, ether, benzene, chloroform and castor oil, and can dissolve nitrocellulose, cellulose acetate, acrylic resin, polyvinyl acetate, etc. Triacetin is widely used in tobacco, food, metallurgy and other industries. It can be used as a solvent for photo film and preservatives, as well as an emulsifier, spice fixative, and plasticizer. [0003] Various methods for preparing triacetin have been disclosed in the prior art. Among them, the most commonly used one is to synthesize triacetin from glycerol and acetic acid. This method uses concentrated sulfuric acid as a catalyst, and glycerol and acetic acid react intermittently in a batch reactor to ge...

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Problems solved by technology

[0006] In the prior art, since the reaction to generate the intermediate product and the reaction to produce the final product are carried out in the same reactor, the reaction to generate the intermediate product will be affected by the reaction to generate the final product, resulting in a slower reaction rate and affecting the final product. Yield

Moreover, because the raw materials have not fully reacted, the concentration of acetic acid in the removed water will be very high. When the water and the water-carrying agent are removed by azeotropic distillation, a large amount of raw material acetic acid will also be removed thereupon, and the reduction of the raw material concentration will also Reduce the rate of the esterification reaction that produces intermediate products, prolong the reaction time of the esterification reaction, and ultimately reduce the yield of the final product, resulting in increased cost consumption

At the same time, using concentrated sulfuric acid as a catalyst also has a series of problems: the catalyst concentrated sulfuric acid severely corrodes the equipment; the raw material acetic acid will be lost when adding alkali to neutralize the concentrated sulfuric acid; the generated acetate and sulfate will entrain the reaction product when discharged; concentrated Sulfuric acid has strong oxidizing properties, resulting in the formation of various by-products, etc.

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