(1) Direct hydrolysis process: add 1,2-dichloropropane, water, sodium bicarbonate and hexadecyltributylphosphorus bromide together into the reaction kettle, and react at 100℃ for 18h under carbon dioxide partial pressure of 1.0MPa. 80% propylene glycol is obtained. Control the feeding speed of dichloropropane, that is, the feeding speed is fast at high temperature and slow at low temperature. Example: add 60g calcium carbonate and 150g water in a 300mL autoclave, stir and heat up to 230°C, and continuously add dichloropropane at a speed of 0.03g/(min·100g H2O) for 11.5h; continue stirring at this temperature for 30min, then After quenching to room temperature, the yield of propylene glycol is about 95%. Control the temperature within 130-300 ℃, as long as the feed rate of dichloropropane is changed accordingly, the yield of propylene glycol can reach more than 95%.
(2) Two-step hydrolysis process: firstly, the raw materials are reacted in a kettle-type reactor, and after the dichloropropane reaches a certain conversion rate, it is poured into a plug flow reactor to continue the reaction, and finally hydrolyzed into propylene glycol. Example: add 606kg of dichloropropane into a 2 cubic meter reactor, add 800kg of sodium acetate, 556kg of 1,2-propanediol, 10kg of acetic acid and 1kg of water, stir and heat up to 180°C, cool to 120°C after 4 hours, extract the material, The preheater was heated to 180°C, passed through a plug-flow reactor with a length of 400m, an inner diameter of 25mm, and a volume of 230L at a speed of 500L/h. The product was collected in the second stirred tank, cooled to room temperature, and the analyzed product was: 44 kg dichloropropane, 334 kg propylene glycol, 32 kg sodium acetate, 44 kg acetic acid, 234 kg 1,2-diacetoxypropane, 693 kg propylene glycol monoacetate, 45 kg 1-chloropropene, 547 kg NaCl and 1 kg water.