Study On Separation Of Azeotrope Mixtures By Batch Extractive Distillation

The solvent selection for extractive distillation and separation of azeotropic mixtures by batch extractive distillation were studied via theoretical analysis and the experiment.A solvent selection method using group contribution combined with molecular design was proposed, according to this method, dimethyl benzene, trimethyl- benzene,isopropylbenzene,diethybenzene,1,3-dimethyl-5-ethylbenzene, 4-tert- butyl toluene,butylbenzene were selected as solvents for separation of acetonitrile-toluene mixture by batch extractive distillation.The vapor-liquid equilibria of acetonitrile -toluene with different solvents were calculated using UNIFAC group contribution method.The vapor-liquid equilibria of acetonitrile-toluene-isopropyl benzene,acetonitrile-toluene-4-tert-butyltoluene and acetonitrile-toluene-1,4-diethy benzene were measured by the vapor-liquid equilibria experiments.The Wilson activity coefficient equation parameters of acetonitrile-4-tert-butyltoluene, toluene-4-tert-butyltoluene,acetonitrile-1,4-diethybenzene and toluene-1,4-diethy benzene were correlated from experiments data. Different solvents were investigated experimentally by batch extractive distillation,then the effects of different operation parameters to batch extractive distillation process were studied.Ethylene glycol was selected as solvents for separation of acetonitrile-water mixture by batch extractive distillation. The vapor-liquid equilibria of acetonitrile- ethylene glycol was measured by the vapor-liquid equilibria experiments,and the Wilson activity coefficient equation parameters were also obtained from experiments data.The experiment results show that ethylene glycol is the effective solvent.Batch"azeotropic-extractive"distillation was presented, and the separation of cyclohexane-butylamine using water as solvent was studied by such process.