Study On The Melting Crystallization Process Of N-phenylglycinonitrile

N-Phenylglycinonitrile is an important chemical intermediate which is widely used in the production of industrial fiber dye indigo and other chemical products.With the continuous expansion of the global indigo market,the production and quality of N-Phenylglycinonitrile are required to be higher.In this paper,a new technology for refining and purifying N-Phenylglycinonitrile by melt crystallization has been developed,which provides basic data and theoretical guidance for engineering amplification and industrial design.Firstly,the basic thermodynamic data of N-Phenylglycinonitrile system,such as melting point,melting enthalpy and constant pressure specific heat capacity,were determined by differential scanning calorimetry(DSC).The solid-liquid equilibrium of N-Phenylglycinonitrile system was studied.The experimental results supplement the basic thermodynamic data of N-Phenylglycinonitrile.It is also shown that the N-Phenylglycinonitrile-water binary system is neither a typical type of solid solution nor a type of low eutectic.The dynamic behavior of N-Phenylglycinonitrile was investigated by differential scanning calorimetry.The growth rate of the crystal layer had an important influence on the structure of the crystal layer and the deposition of the mother liquor.The growth rate of the crystal layer was influenced by many factors.The most important factors were the temperature of the solid-liquid interface and the cooling rate.The effect of the cooling rate on the growth rate of N-Phenylglycinonitrile crystals was studied.On the basis of thermodynamics and kinetics studies,the purification process of N-Phenylglycinonitrile is systematically studied.The effects of crystallization rate,crystallization end temperature,sweating rate and sweating end temperature on the purity and yield of the product are mainly investigated.Finally,a new type of purity technology of N-Phenylglycinonitrile is developed.The experimental results show that the purity of N-Phenylglycinonitrile can be achieved by melting crystallization process developed in this paper.The material balance of the melt crystallization workshop of N-Phenylglycinonitrile with annual output of 3000 tons is designed.The purification process of N-Phenylglycinonitrile melt crystallization developed in this paper has a good industrial value.