Study On Separation Of DMF - Toluene - Water Mixture By Extractive Distillation And Distillation

The application of N,N-dimethylformamide and toluene in medication and chemical industry etc, was summarized in the paper, and the manufacturing techniques of them were also introduced in this paper. Based on many literatures domestic and overseas, with ordinary methods, to separate N,N-dimethylformamide from mixtures was generalized systematically. A method of combining extractive distillation with distillation was proposed in the paper for the purpose of simplified production technology, environmental care, increasing. N,N-dimethylformamide’s purity to99.00%(wt%) and also recovering toluene. Hence, this paper is of great significance to the comprehensive utilization and governance of the waste water which contained N,N-dimethylformamide and toluene.The effect of various solvents on separation of N,N-dimethylformamide, toluene, water system was analyzed in terms of polarity judgment and intermolecular forces. Esters, polyols, amines, ketone and sulfone were considered preliminary as suitable extractants for this system. Simulation results of single-state extractiom distillation in different solvents were obtained with ASPEN PLUS simulation software. Based on the results and contrastive analysis, dioctyl phthalate is chosen as the extractive agent in N,N-dimethylformamide-toluene-water mixture. Column chromatographic method was finally applied to verify the extraction of phthalate. Consequently, dioctyl phthalatewas chosen as extractive agent.Extractive distillation process was simulated by using ASPEN PLUS software. The six references effecting of solvent ratio, top product quantity, reflux ratio, theoretical plate number, solvent position and material position on extractive distillation simulation were discussed in this paper. According to the simulation results, the orthogonal experiment of six factors and three levels was designed to optimize the conditions of extractive distillation process. Simulation results showed that the purity and yield of N,N-dimethylformamide were up to99.99%and92.26%under the optimized conditions. A theoretical basis for further tests was provided for this study.Confirmatory experiments were carried out based on the results of the extractive distillation and distillation simulation. Experimental results indicated that N,N-dimethylformamide purity up to99.98%and its yield up to91.58%. And then, purity99.57%and yield98.96%of toluene was obtained at the tower top output by distillation process, and also the purify99.20%water below was got. The experimental results were similar to the simulation results, which verified the accurity of the simulation results.The results of combining extractive distillation and distillation were provided in the paper, which can meet the need of further test and industrial application.