Study On Adsorption Separation Method Of High-purity Acetonitrile

As a mobile phase of high performance liquid chromatography and a common organic solvent,high-purity acetonitrile requires extremely high purity and is in great demand.At present,domestic high-purity acetonitrile mainly relies on imports.Therefore,the research on separation technology of high-purity acetonitrile is of great significance for localization.In this paper,activated alumina and commercial molecular sieves were used for adsorption and purification.The novel long-chain imidazolium salt was used as a structure-directing agent to synthesize a novel molecular sieve with ZSM-5 structure.The specific surface area reached 508.61 m~2/g.After calcination,it has a stable mesoporous structure with an average pore diameter of 4.19 nm and is used in acetonitrile purification.The types of impurities in the raw materials and the content of impurities after the treatment were analyzed by means of gas chromatography-mass spectrometry.The pore size and surface acidity of the molecular sieve are better than that of activated alumina.The maximum decrease of the absorbance at 190 nm,200 nm,240 nm and254 nm of the sample after adsorption is over 58%.Rectification,as an important means of separation of organic matter,can achieve a good separation effect on high-boiling impurities in this experiment.In this paper,a two-step batch operation method for adsorption combined rectification is proposed.After the adsorption operation and the rectification operation,the absorbance of the product in the short wavelength range is less than 1,and the absorbance in the long wavelength range is less than 0.01.The rectification method compensates for some of the high-boiling impurities that are difficult to be treated by the adsorption method,and the adsorption step preliminarily separates some of the azeotropic impurities,so that the sample after rectification absorbs light lower.After 5 hours of adsorption at room temperature,the filtrate was filtered for rectification.After refluxing for 2 h,the reflux product was extracted at a ratio of 20:1.The absorbance of the obtained product was closer to the absorbance of imported high-purity acetonitrile than the domestic chromatographic grade acetonitrile.It has a good industrial application prospect and proposes an improved idea for the future purification process for the localization of high-purity acetonitrile.