A Study On The New Technology For Synthesis And Separation Of Glycine

Glycine is an important chemical intermediate product, which is widely applied in thearea of pesticide, medicine, animal feed, etc. More attention was paid to its synthesis andseparation technology. China is one of the main countries producing glycine. The mainproducing technology is through the ammoniation of chloroacetic acid. The key problemexisting in the industrial producing process is the separation of glycine from ammoniumchloride by the diluents crystallization with methanol. The main disadvantages of thisseparation technology include the high cost of methanol, the vent of wastewater, theserious pollution, the high consumption of energy and reactant, which will cause the highproducing costs and the low competitive position.In this paper, the reaction mechanism was studied and the influence of the keyelements, such as temperature and pH,on the synthesis process of glycine wasinvestigated. By improving the traditional producing technology of glycine, an advancedsynthesis and separation technology was introduced. Ammonium monochlord acetic acidand ammonium bicarbonate were used as the stuffs;the reaction between them was carriedout in the common saturated solution of glycine and ammonium chloride.Three new methods, namely, the phase separation method, the electrodialysismembrane method and the cooling crystallization method, were used in the separationprocess between glycine and ammonium chloride. Compared with the traditionalproducing process, the use of methanol was avoided, investment of equipments was less,and the consumption of catalyst would be greatly reduced in the present technology. Thetwo high quality products, glycine and ammonia chloride, can be obtained. Additionally,the headache of the serious pollution in the traditional process could be solved. By use ofthe new synthesis and separation technology developed in this paper, the total yield of theglycine with a purity of 98% was exceeds 87%, the effect of electrodialysis was 88%, thepower consumption per ton of glycine were 247kwh. The new technology has manyadvantages, such the low producing cost, the low energy consumption, the convenientoperation, the low pollution, thus, has an industrial prospect.