Selection of Solvents of C 9 Aromatic Hydrocarbons Extractive Distillation by Gas Liquid Chromatography
色谱法筛选C_9芳烃萃取精馏溶剂

The extractive distillation is a very important method for the separation of chemicals with nearly the same boiling points. Selectivity (S) was used as a parameter for separation. The more the S is apart from 1, the better the solvent for separation is. S can be obtained from the ratio of the adjusted retention times in GC easily. Seven solvents for extractive distillation with regard to C 9 aromatic hydrocarbons were tested as stationary phases in gas liquid chromatography at different temperatures. The solvents are solfolane, DEG, N methyl 2 pyrrolidone and 4 phthalates. From the experiments we can conclude: (1) The selectivities of these solvents decreased to different extent with temperature rising. Hence low temperature is better for separation of C 9 aromatic hydrocarbons. (2) These solvents have different effects on selectivities, because there are different forces between the solvents and C 9 aromatic hydrocarbons. It is obvious that polarities of solvents have certain effects on selectivities. But it is not absolutely right that the stronger the polarity is, the better the effects are. (3) Among these seven solvents dimethyl phthalate is better for separation of C 9 aromatic hydrocarbons. Dioctyl phthalate and N methyl 2 pyrrolidone are also good choices for extracting 1,3,5 trimethylbenzene from C 9 aromatic hydrocarbons.