(1) 1000L of crude mother liquor in the production of propyl gallate passes through MVR thin film evaporator, and evaporative concentration obtains 925L of condensed water and concentrated solution 75L; A mixed solution of 20% content, 35% propyl gallate content, 2% gallic acid content and water).
(2) drop into gallic acid 300kg, n-propanol 1200L and recovery mixed solution 70L (catalyst) in 2000L enamel reaction kettle as raw material, be heated to reflux, carry out high temperature esterification reaction at 100 DEG C for 8 hours, the water that the reaction generates is reacted The kettle is equipped with a membrane dehydration system to separate the water.
(3) n-propanol is recovered by distillation after the reaction finishes, and when 800L of solvent is recovered, the recovery is stopped, and 1000L of refined mother liquor is added to the reactor, and the remaining 200L of solvent is continued to be recovered (when the temperature in the reactor reaches 95～99 ℃, the recovery is stopped);
(4) the liquid that reclaimed the solvent was transferred into the 2000L enamel crystallization kettle, carried out crude crystallization, and was cooled to 20 ℃ after thick centrifugation to obtain propyl gallate crude crystal 422kg (water content 15%) and crude mother liquor 940L (wherein The sulfuric acid content was 1.4 wt%, the propyl gallate content was 2.5 wt%, and the gallic acid content was 0.14 wt%).
(5) in 2000L enamel decolorization kettle, add 1500L soft water, 422kg of propyl gallate coarse crystal, activated carbon 6kg and EDTA disodium 0.5kg; be heated to 95 ℃ to dissolve, decolorize for 30 minutes, fine filter;
(6) fine filtrate is transferred into fine crystallization in 2000L enamel crystallization kettle, and fine centrifugation after cooling to 20°C, obtains 394kg (water content 14.5wt%) of fine propyl gallate crystal and 1450L of fine mother liquor (wherein propyl gallate) The content is 2.5wt%);
(7) 394kg of propyl gallate crystals are put into 2000L enamel cone-type rotary vacuum dryer, and dried under vacuum-0.095Mpa for 12 hours to obtain 336kg of propyl gallate, content 99.5%, and conversion yield 112%; The consumption of n-propanol is 200L (weight 157.1kg); the consumption of sulfuric acid is 14kg.
(8) 925L of evaporated condensed water (chromaticity is 50, pH value is 6, CODcr 1000mg/L) is treated by sewage to reach “Urban Sewage Recycling and Urban Miscellaneous Water Quality” (chromaticity is 20, pH value is 6.5, CODcr 15mg /L).
First select the feeding ratio: gallic acid: n-propanol: cyclohexane: aromatic sulfonic acid = 1: 3: 2.1: 0.1, then accurately weigh 500g of gallic acid, 1500g of n-propanol, 1050g of cyclohexane and aromatic acid according to this ratio Sulfonic acid 50g.
Operation steps: The first step is to add gallic acid, n-propanol, cyclohexane and aromatic sulfonic acid to the reactor with overflow pipe at the same time, and carry out the esterification reaction at 65 ° C and under stirring conditions, and remove water at the same time. , the reaction time was 15 hours. In the second step, the reaction material obtained in the first step is subjected to distillation and material separation, and the temperature of the distillation is gradually increased from 65°C to 100°C, and the temperature at the end of the distillation can reach 110°C to ensure the distillation effect. The crude propyl gallate product obtained after distillation and its trace amount of aromatic sulfonic acid enter the next treatment process, and n-propanol and cyclohexane are recycled as raw materials again. In the third step, the crude propyl gallate product obtained in the second step and its trace aromatic sulfonic acid are washed with 100 ° C of boiling water to remove the aromatic sulfonic acid on the surface of the gallic acid, and the feeding ratio is: water: propyl gallate crude product = 1:5. In the fourth step, the material obtained in the third step is cooled and filtered to obtain a crude product of propyl gallate after deacidification. The temperature of the material during cooling is reduced from 100°C to 15°C. The 5th step carries out recrystallization with 100 ℃ of boiling water of the propyl gallate crude product that the 4th step obtains, adds decolorizing agent activated carbon simultaneously and carries out decolorization (generally carry out twice), the feed ratio is: propyl gallate crude product: water : decolorizing agent=1:2:0.3, in the sixth step, the material obtained in the fifth step is cooled and filtered to obtain a refined product of wet propyl gallate, and the temperature of the material during cooling is reduced from 100°C to 15°C. In the seventh step, the wet propyl gallate refined product obtained in the sixth step was dried at 60° C. for 20 hours. Thereby, 465 g of propyl gallate finished product was obtained, and the yield was 93.0%.
The raw material Gallatia japonica, powdered, passed through a 40-mesh sieve, took 100 g of gall folded powder and 1,000 ml of n-propanol, stirred and extracted at 50 ° C for 4 hours, and added 5 g of activated carbon and 10 g of refined diatomite adsorbent to the feed solution for decolorization 30 minutes, followed by vacuum filtration. The filtrate was added with 25 ml of sulfuric acid with a catalyst concentration of 80%, reacted at 80 °C for 5 hours, cooled to 20 °C and filtered, the filtrate was evaporated and concentrated under reduced pressure, and the evaporated solvent n-propanol was recovered; the concentrated material was dissolved in 500 mL of hot water at 80 °C , stirred, cooled to 15°C, crystallization was centrifugally filtered to obtain 56.8g wet crystals of gallic acid propanol, the crude product was dissolved by heating with 750ml of water, decolorized with 2g activated carbon for 30 minutes, vacuum filtered, and the filtrate was cooled to 10°C for crystallization for 5 hours. Centrifugal filtration, washing the material until the pH is 6.0-7.0, taking the filter cake and drying in vacuum (60° C.) to obtain 32.6 g of propyl gallate finished product with a content of 99.5%.
Report Four.
9.41g of gallic acid monohydrate, 25mL of n-propanol and 3.68g of N-acetoxypyridine hydrogen sulfate ionic liquid were added to the reaction vessel, and the reaction was carried out at reflux temperature. After the reaction, the reaction device was changed to a distillation device, and the pressure was reduced first and then reduced. The excess n-propanol was evaporated, then deionized water was added and slowly cooled to complete crystallization, and a white solid product was obtained by suction filtration, namely propyl gallate, with a yield of 94%. The water-containing ionic liquid can be recycled after dehydration by rotary evaporation and vacuum drying.
