Study On The Cleaner Production Process Of Hydantoin

Hydantoin,an important intermediate,can be widely used in medical,pesticide,chemical engineering and spin industry. In this paper the property,application andpreparation developments of hydantoin are reviewed. Moreover,some optimizationconditions by using normal pressure method are found. Noteworthily, a new reactor——packed column is firstly created into the synthesis of hydantoin. Also it is modifiedinto trickle bed reactor to produce hydantoin by using mixed gas which is let off fromthe normal pressure reactor. The two ways are succeed in the preparation of hydantoinand they are both clean and high efficiency. The gas in the preparation can be circularusing. They can be truly called cleaner production process. The main contents andinnovations are as follows: Hydantoin is synthesized by blender in normal pressure. It is used ammoniumbicarbonate and glycolonitrile as raw materials, when 66ml glycolonitrile and 150gammonium bicarbonate are mixed after 4 hours at 85℃,and the yield of hydantoin is85.8%. Carbon dioxide is aerated in the whole process at the speed 0.25m3/h. It is researched on the cleaner production process of preparation of hydantoin. Atfirst it is used ammonia and carbon dioxide as raw materials ,when ammonia isaerated in 1 hours at the speed 0.25m3/h and carbon dioxide is aerated in 3 hours atthe speed 0.25m3/h, after 3 hours under 85℃,and the yield of hydantoin is 80.3%.Then by using self-made packed column it is found that disordered filling 150 g L2Raschig rings, reversed flowing gas and liquid, aerated ammonia in 1 hours at thespeed 0.2m3/h, aerated carbon dioxide in the whole process at the speed 0.3m3/h, theyield of hydantoin is 69.4% at 80-100℃(the temperature of clamp ferrule) under135-180ml/h of liquid speed. Furthermore when the reactor is modified into tricklebed reactor, it is used 200g strong acidic resin as catalyzer and gas and liquid arereversed.By using the mixed gas from the blender, it is found that at the speed 0.5m3/hand the liquid speed at 150 ml/h, the total yield of hydantoin is 65.8% at 80℃ (thetemperature of clamp ferrule). Producing hydantoin by packed column and trickle bed reactor is developed IIfirstly in China. New reactors are used not only acquiring product continuously andefficiently, but also eliminating the exhaust gas and waste liquid. In addition,thepresent study is not reported previously in China.