Study On The Melting Crystallization Process Of Succinonitrile

Succinonitrile is a colorless,odorless wax.It can be used as a reagent,and also used in the production of nylon and pharmaceutical intermediates.At the same time,It is also an important additive for electrolyte of lithium-ion batteries.Currently,there are three methods for refining and purification Succinonitrile: solution crystallization,adsorption,and decompression intermittent distillation.But those methods have many problems such as high energy consumption,long experimental period,and low purity.In this thesis,adopting the advantages of melt crystallization technology,the melt crystallization process of Succinonitrile is systematically investigated.Meanwhile,we have developed a new separation technique to use melt crystallization purify Succinonitrile,and also provided necessary basic experimental data for process amplification.The differential scanning calorimetry(DSC)was used to measure the solid-liquid phase diagram of Succinonitrile.Which is appeared as eutectic system according to the experimental result.The kinetic behavior of the static melt crystallization of succinonitrile was investigated by means of DSC.Non-isothermal crystallization kinetic models such as Jeziorny model,Ozawa model,improved Ozawa model,Kissinger model were firstly introduced to process the kinetic experimental data of Succinonitrile system.The results of all the models were compared and the kinetic parameters of models were obtained which reveal the mechanism of static melt crystallization of Succinonitrile.Activation energy for non-isothermal crystallization of succinonitrile is ?E =-811.56 J/mol by Kissinger equation.For the succinonitrile which purity is 99.84%,the static melt crystallization was adopted to purify succinonitrile and the effect of cooling rate,the final crystallization temperature,the sweating rate and the final sweating temperature were systemically studied.Besides,the orthogonal experimental design method was used to determine the optimal crystallization condition.The raw material was crystallized at 47°C with cooling rate of 0.025°C/min and sweated at 56°C with sweating rate of 0.03°C/min.