Method 1: A preparation method of high-content triacetin, using the acid-alcohol esterification reaction mechanism, the esterification reaction adopts rectification technology, and glycerol, glacial acetic acid, acid catalyst, and azeotropic water agent are added with rectification. The reaction is carried out in the reaction kettle of the tower, the condenser and the water separator, and the water produced by the reaction is continuously extracted at the top of the tower, and the azeotrope is refluxed into the tower. The crude product is sent to the acylation kettle, and deacidification is added after the acetic anhydride reaction to obtain the Glycerol Triacetate crude product; The dosage of activated carbon is 0.05-0.1% of the quality of the crude 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 condenser to condense the water, turn on the heating oil valve to heat up, and at the same time introduce 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, when the kettle temperature reaches 125°C, close the heat transfer oil heating valve, control 115°C, control the vacuum degree ≤300pa for fractionation, collect the first fraction, collect Then, it is pumped into the deacidification tank in the process of preparing the crude Glycerol Triacetate, and enters the next round of preparation. The reaction product is cooled with jacket cooling water, cooled to less than or equal to 60°C, and then the jacket residual water is drained. While cooling, the circulating filtration operation is carried out; the 1000-mesh wool felt filter is used for circulating filtration, and the pressure during circulating filtration is 0.2MPa. The carbon residue in the filter should be cleaned up before filtration.
After circulating filtration to obtain a clear and transparent feed liquid, press it into the finished product tank to obtain the refined Glycerol Triacetate; the content of the prepared triacetin product is ≥99.7%, the chromaticity is less than No. 15, and the acid value is ≤0.007%. Continuous refining of the crude product can remove impurities, reduce the moisture content, make the acid value of the product qualified and improve the bad smell of the product. Continuous refining can improve the refining yield to achieve the purpose of increasing the product content. :
Method 2: a preparation method of Glycerol Triacetate, comprising the following steps:
(1) Introduce glycerol and acetic acid into the reactor, and add catalyst and dehydrating agent at the same time;
(2) After the feeding is completed, the temperature of the reactor is raised, the vent valve of the reactor is opened, and after refluxing, the reflux rate is controlled to 1200~2000L/h, the temperature of the kettle is raised to 110℃, the temperature of the top of the kettle is controlled at 80~100℃, and the reflux liquid is collected, The whole process lasts 20 to 24 hours;
(3) Turn on the vacuum pump to carry out deacidification, and raise the temperature of the reaction kettle at the same time. When the temperature of the kettle rises to 135-140 °C, the deacidification is terminated, and acetic anhydride is added to the reaction kettle;
(4) Continue to heat the reactor to 140°C, keep the temperature for half an hour, and add barium hydroxide through the feeding port;
(5) Continue to heat the reaction kettle, when the temperature of the kettle reaches 200~205℃, turn on the vacuum pump to carry out vacuum distillation for 2~4 hours, and transfer the feed liquid in the kettle to the crude product storage tank;
(6) Pass the crude product through nitrogen pressure filtration to obtain the fine product and put it into storage.