Method 1: A method for preparing high-content glycerol triacetate, using the mechanism of acid alcohol esterification reaction, the esterification reaction adopts rectification technology, and glycerin, glacial acetic acid, acid catalyst, and azeotropic water agent are added The reaction is carried out in the reaction kettle of the tower, condenser and water separator, and the water produced by the reaction is continuously removed at the top of the tower, and the entrainer is returned to the tower. Thick product is sent in the acylation still, deacidifies after adding acetic anhydride to react, and makes triacetin crude product;: Put the measured triacetin crude product into refining still, drop into the active carbon soaked with triacetin in advance . The dosage of activated carbon is 0.05-0.1% of the mass of the crude product of glycerol triacetate; after cleaning the filter system, add activated carbon as appropriate according to the clarification of the feed liquid during the reflux cycle.
Turn on the condensate water in the condenser, turn on the heating oil valve to raise the temperature, and at the same time, let in an appropriate amount of nitrogen for bubbling. Decolorization for 2.5-3 hours; when the temperature of the refining kettle reaches 110°C, control the vacuum degree ≤ 300pa, close the heat transfer oil heating valve when the temperature of the kettle reaches 125°C, control 115°C, control the vacuum degree ≤ 300pa Fractional distillation, collect the initial fraction, collect Then it is pumped into the deacidification tank in the process of preparing the crude triacetin, and enters the next round of preparation. The reaction product is cooled by opening the jacket cooling water, and after cooling to less than or equal to 60°C, the remaining water in the jacket is drained. Perform circulation filtration operation while cooling down; use wool felt filter with a pore size of 1000 mesh for circulation filtration, and the pressure during circulation filtration is 0.2MPa. The carbon residue in the filter should be cleaned before filtering.
After circular filtration to obtain a clear and transparent material liquid, press it into the finished product tank to obtain the refined triacetin; the content of the prepared triacetin product is ≥99.7%, the chroma is less than No. 15, and the acid value is ≤0.007%. Continuous refining of crude products can remove impurities, reduce moisture content, make the acid value index of the product qualified and improve the bad smell of the product, and continuous refining can improve the refining yield to increase the product content. :
Method 2: a preparation method of triacetin, comprising the following steps:
(1) Introduce glycerin and acetic acid into the reactor, and add catalyst and dehydrating agent at the same time;
(2) Raise the temperature of the reactor after feeding, open the vent valve of the reactor, and after reflux, control the reflux flow rate to 1200~2000L/h, raise the temperature of the kettle to 110°C, control the temperature of the top of the kettle at 80~100°C, collect the reflux liquid, The whole process lasts 20-24 hours;
(3) Turn on the vacuum pump for deacidification, and increase the temperature of the reactor at the same time. When the temperature of the reactor rises to 135~140°C, the deacidification is completed, and acetic anhydride is added to the reactor;
(4) Continue to raise the temperature of the reactor to 140°C, keep it warm for half an hour, and add barium hydroxide through the feeding port;
(5) Continue to heat the reactor. When the temperature of the reactor reaches 200~205°C, turn on the vacuum pump for vacuum distillation, which lasts for 2~4 hours, and transfer the liquid in the reactor to the crude product storage tank;
(6) Filter the crude product through nitrogen pressure to obtain the refined product and put it into storage.
