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Separation Of Cyclohexane-THF By Extractive Distillation With Salt

Posted on:2009-03-29Degree:MasterType:Thesis
Country:ChinaCandidate:Q WenFull Text:PDF
GTID:2121360272486432Subject:Pharmaceutical Engineering
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Cyclohexane and THF are very important intermediate in organic synthesis. They are widely used in covering material, adhesive and so on. But this mixture is so hard to be separated by conventional distillation because they are bound to form azeotrope. So this paper discusses the batch salt-extractive distillation using NaSCN dissolved in DMF as the extractive solvent to separate the mixture.Firstly, the vapor-liquid equilibrium curve of Cyclohexane -THF was determined by experimental data. The result verified that azeotrope would be formed when cyclohexane at a mass concentration of 15% . Then the selection of extractive solvent of the binary mixture using UNIFAC group contribution method and the validation of the effect of the solvent through the vapor-liquid equilibrium experiment are carried out. The feasible solvent ratio is also investigated. The experiment results showed that to some extent DMF can increase the relative volatility of Cyclohexane–THF system.Secondly, three kinds of salt NaSCN,NaNO3,KI are selected, the experimental data verified NaSCN is the best salt to separate this azeotropic system. Then this paper investigates the effect of salt concentration, the result showed that relative volatility will rise according to the rise of salt concentration at the low concentration range, when the concentration goes to the high range the result is contrary. So 8~13% will be the flexible concentration range during the experiment.Thirdly, the small scale batch salt extractive distillation was done to separate the binary mixture. In these experiments, the effect of the operation parameter such as solvent flow rate and solvent ratio were studied. The result of the experiment showed that 10ml/min flow rate, 1:1 solvent ratio and 13% NaSCN concentration is the suitable operation condition.At last, this paper analyses action principle of the solvent with salt. Then the simulation of the distillation process was carried out by Rose relaxation method using the VLE experimental data. The simulation results and the above experiment data show good agreement.
Keywords/Search Tags:Extractive Distillation with Salt, Salt Effect, Vapor-Liquid Equilibrium, Simulation
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