Weigh 200 kilograms of phosphorus pentoxide with a content of 98.20% (mass percentage, the same below), put 189.7 kilograms of them into a clean, dry 500-liter reactor, and introduce 250 kilograms of metered content 98.5% trifluoroacetic acid into High drop in the tank. Check that the joints are well sealed, and the emptying pipelines at the top of the distillation column and the receiving tank are unobstructed. Open the deep well water pump and let the condensed water into the condenser to circulate, and start to drip phosphorus pentoxide at a rate of 0.15 liters/min. After 10 minutes, adjust the dripping rate to 0.4 liters/min. After 10 minutes, adjust to 1.2 liters/min, 10 minutes later to 1.8 liters/min, 10 minutes later to 2.8 liters/min, 10 minutes later to 3.8 liters/min, until the dripping is completed, close the dripping pipeline valve. At this time, the temperature of the gas phase in the kettle was 82°C. After 20 minutes, the temperature of the kettle was 65°C, and the jacket of the kettle began to be fed with steam. After 15 minutes, the temperature of the kettle rose to 72°C, and the steam was turned off. After 16 minutes, the temperature of the kettle was 80°C, the kettle boiled, and there was reflux at the bottom of the tower. At this time, the tower body was heated to 35°C with a pressure regulator, raised to 45°C after 5 minutes, and the reflux reaction was maintained for 80 minutes at a kettle temperature of 80 to 90°C and a tower temperature of 40 to 45°C. After the reflux reaction is completed, while maintaining the above-mentioned kettle temperature, tower temperature and reflux state, observe that the temperature at the top of the tower is 39.2 ° C, and open the product tank receiving valve to start collecting the product. Control the feeding speed at 1.0-1.2 liters/min, and keep the temperature at the top of the tower between 39-40.5°C. After 2 hours, 132 liters of finished products have been received. At this time, the temperature at the top of the distillation column rose to 40.6 °C, and the closing valve was closed to allow the system to fully reflux. The temperature of the kettle was raised to 100°C, the temperature of the tower body was raised to 50°C, and the temperature of the tower was 40.1°C after 10 minutes, the receiving valve was opened, and the finished product was continued to be collected at a speed of 0.6 liters to 0.8 liters/min. After 20 minutes, the top of the tower was The temperature rises to 40.6 °C again, close the receiving valve, continue full reflux until the temperature at the top of the tower drops to 40.2 °C, open the receiving valve and continue to collect the finished product at a speed of 0.2 liters to 0.4 liters/min. When the temperature rises to 40.8°C, the finished product receiving valve is closed, and the finished product is stopped. Open the collection valve of the back distillation tank, and change the collection of the back fraction. At this time, the collection valve is fully opened, and there is no need to control the collection speed. After 10 minutes, the temperature at the top of the column has risen to 56°C, and there is no more reflux, and the end-distillate collection valve is closed. Close the valve at the bottom of the tower and turn off the heating of the tower body. Turn off the steam in the jacket of the kettle, discharge the waste heat from the jacket of the kettle, and cool it with water in the deep well. When the temperature in the kettle dropped to 40°C, the water measuring tank was opened, and 148 kg of recovered steam condensed water measured in advance was dripped into the kettle at a rate of 0.2 liters/min, and the jacket cooling water was kept circulating. After 20 minutes, the water droplet acceleration was adjusted to 0.6 liters/min, and after 20 minutes, it was adjusted to 1.8 liters/min until the addition was complete. It was observed that when all the materials in the kettle became liquid and the temperature was lower than 35°C, the by-product phosphoric acid was released. Drain the condensed water from the jacket of the kettle, enter a small amount of steam, open the vent valve of the kettle, and dry the water vapor in the kettle for use. In this process (1), 142 liters × 1.51 = 214.42 kilograms of product trifluoroacetic anhydride were obtained, the purity was 99.2%, and the yield was 85.8% in terms of trifluoroacetic acid, and 16.8 liters (25.64 kilograms) of back fraction and tail gas condensed mixture were obtained. ), 366 kg of by-product phosphoric acid was obtained, and the content was 75.2%. Then, 16.8 liters (25.64 kg) of the recovered fraction and the condensed mixture of tail gas were introduced into the high-level dropping tank, and the remaining 10.3 kg of phosphorus pentoxide was put into a 50-liter dry and clean reaction kettle. . Pass the deep well water into the condenser for circulation, and start to drip the recovered mixture at a rate of 0.2 liters/min. After 10 minutes, change the dripping rate to 1.8 liters/min. Until the dripping is completed, close the dripping pipeline valve. At this time, the temperature in the autoclave was 70°C, and it was allowed to react spontaneously. After 10 minutes, steam was introduced into the jacket of the kettle to raise the temperature of the kettle to 76°C, and the steam was turned off. After 5 minutes, the temperature of the kettle reached 81°C, the kettle boiled, and there was reflux at the bottom of the tower. At this time, the tower body was heated to 35°C with a pressure regulator and gradually increased to 45°C, and the reflux reaction was maintained for 60 minutes at a kettle temperature of 80 to 90°C and a tower temperature of 40 to 45°C. After the reflux reaction was completed, while maintaining the above-mentioned kettle temperature, column temperature and reflux state, the temperature at the top of the column was observed to be 39.4°C, and the product was collected. Control the feeding speed at 0.2 to 0.4 liters/min, and keep the temperature at the top of the tower between 39 and 40.5 °C. After 20 minutes, the temperature at the top of the tower rose to 40.7°C, and the back-distillation collection valve was closed to allow the system to fully reflux. The temperature of the kettle was raised to 100°C, the temperature of the tower body was raised to 50°C, and the temperature of the top of the tower was 40.8°C after 10 minutes. At this time, the receiving valve is fully opened. After 5 minutes, the temperature at the top of the tower has risen to 55 ° C, and there is no more reflux. Close the back-distillation receiving valve, close the bottom valve, and turn off the heating of the tower body. Close the jacket of the kettle and discharge the waste heat side by side, and enter the deep well water for cooling and circulation. When the temperature in the kettle dropped to 40°C, the water metering tank was opened, and 12 kg (liter) of recovered steam condensed water was added dropwise to the kettle at a speed of 0.2 liters/min, and the jacket cooling water was kept circulating for 60 minutes. added later. It was observed that when all the materials in the kettle became liquid and the temperature was lower than 35°C, the by-product phosphoric acid was released. Drain the condensed water from the jacket of the kettle, enter a small amount of steam, open the vent valve of the kettle, and dry the water vapor in the kettle for use. In this process (2), 7.4 liters (11.18 kilograms) of product were obtained with a purity of 99.1%, and 0.12 liters (0.18 kilograms) of the last fraction was obtained, and 16 kilograms of by-product phosphoric acid were obtained with a content of 75.4%. In this process, a total of 214.42+11.18=225.6 kg of trifluoroacetic anhydride is obtained, with a purity of 99.2% and a yield of 90.24% calculated as trifluoroacetic acid.
