DEVICE AND METHOD FOR PREPARING 5-(2-(METHYLTHIO)ETHYL)HYDANTOIN

摘要

Disclosed is a device for preparing hydantoin. The device comprises three stages of static mixing reactors connected in series and a stripping column. A feed port of the stripping column is in communication with a discharge port of the third-stage static mixing reactor. Also disclosed is a method for preparing hydantoin by using the foregoing device. The method comprises: feeding 3-(methylthio)propionaldehyde, sodium cyanide, and an aqueous solution of excessive carbon dioxide and ammonia to the three stages of static mixing reactors connected in series to undergo a continuous three-stage reaction, the pressure in the three stages of static mixing reactors connected in series being controlled to be 1.4-2.6 MPa, the temperature in the first-stage reactor rising with a gradient from 40 °C to 80 °C, the temperature in the second-stage reactor rising with a gradient from 80 °C to 120 °C, and the temperature in the third-stage reactor rising with a gradient from 120 °C to 160 °C; and feeding the liquid flowing out from the discharge port of the third-stage reactor to the atmospheric pressure vapor stripping column, and separating and recycling un-reacted carbon dioxide and ammonia, the liquid flowing out from the bottom of the column being an aqueous solution of hydantoin, and mixed gas discharged from the top of the column being used for recycling and preparing an aqueous solution of carbon dioxide and ammonia. The device and method of the present invention not only can easily achieve gradient temperature rising, high-efficiency mixing, complete reaction, high reaction speed and a small quantity of by-products, but also can achieve convenient and efficient refinement of hydantoin, with a high quality and yield of hydantoin.