Preparation Of Chromatographic Grade Acetonitrile From Industrial Acetonitrile

Chromatography grade acetonitrile is widely used as solvent in such fields as UV spectrophotometer, thin layer chromatography and high performance liquid chromatography et al. Usually Chromatographic grade acetonitrile is obtained by the purification of industrial acetonitrile. At present, purification of industrial acetonitrile mainly depends on the method of distillation after potassium permanganate pretreatment which has the problems of making too much wastes and low productivity. For these reasons, the development of new ways to obtain the chromatography grade acetonitrile has showed a bright prospect and a high value for the practical application.In this paper, chromatography grade acetonitrile had been prepared by using a continuous technology involving oxidation, distillation and adsorption in which ozone was chosen the oxidant. The influence of oxidation, distillation and absorption processes on purification was investigated. Besides, absorbents regeneration conditions and the modification of absorbents for better adsorption capacity were optimized. The results were shown as following:1. The oxidation process was the key step in the purification process, the different oxidation conditions were investigated for the ozone-based oxidation step, and the results showed that in the continuous oxidation process of acetonitrile with input of 10ml/min, gas flow of 250ml/min and ozone concentration of 56.2g/m3, the acetonitrile production could get the best result. And it had been found that the catalytic ozonation treatment by activateed carbon improved ozonation efficiency and the utilization rate of ozone.2. In the adsorption process, the roles of different absorbents and the effects of different combinations of adsorbents was investigated. It was found the activated alumina played a key role in the adsorption and the combined adsorbents of 3A molecular sieves, activated carbon, 13X molecular sieves and activated alumina showed a best adsorbing effect in this work.3. The saturated adsorbents were regenerated by nitrogen sweeping-heat regeneration. It was found that 13X molecular sieves could be totally regenerated by heating for 1h under the condition of 350 centigrade and gas flow of 400ml/min. In the same conditions, activated alumina needed to be heated for 2h for complete regeneration. In order to prepare the better adsorbent,13X molecular sieves was loaded with Mg2+, and the result showed that the adsorption capacity of the zeolite was increased by 12.46%. 4. In the purification process involving oxidation and adsorption, it was found that the quality of the products was highly influenced by the purity of industrial acetontrile. The handling capacity of the fixed bed could be increased by 156% if industrial acetontrile was purified by distillation before adsorption. At last, acetontrile was purified using a continuous technology involving oxidation, distillation, adsorption and distillation, and the product met the qualification of chromatographic grade acetonitrile.