Separation of an Industrial Mixture of Decalin or Naphthalene Fluorination Products. Purification of Perfluoro(7-methylbicyclo[4.3.0]nonane) from Close-Boiling Impurities by Heteroazeotropic Distillation

Abstract

The process of perfluoro(7-methylbicyclo[4.3.0]nonane) (MBCN) purification from an industrial mixture of decalin or naphthalene fluorination products is considered. According to experimental data, distillation separation allows us to concentrate MBCN to a fraction with the target-component content of more than 0.950 wt. fr., after which the process efficiency begins to decrease quickly; upon reaching a concentration of 0.975 wt. fr., separation practically breaks down (the value of the separation coefficient Ksep → 1). The process of purification of MBCN by the method of heteroazeotropic distillation using acetone (Aс) as a separating agent is proposed, the process being realized on a batch semi-industrial distillation column. The method makes it possible to intensify significantly the final stage of purification and to increase the MBCN content from 0.950 to more than 0.998 wt. fr., the mass fraction of the enriched fraction sampling comprises more than 0.85 of the load and the product yield being above 88%. The values of the separation coefficients between the distillate and the bottom product and the coefficients of enrichment for the target and impurity components are given; for the MBСN–Aс binary system, data on the liquid–liquid phase equilibrium and heteroazeotrope characteristics are determined.