Study On The Solvent For The Separation Of Isoparaffin And Naphthene (C₈～C₁₄) By Extractive Distillation

The separation of isoparaffins and naphthenes is one of the problems to be resolved frequently on petrochemical industry. It has been reported the isolation of isoparaffins or naphthenes from C6~C7 hydrocarbons by extractive distillation. In contrast to C6~C7, the separation of isoparaffins and naphthenes (C8~C14) by extractive distillation is more complicated and the related literature is not available.In this paper, D60 and D40 (C8~C14 isoparaffins and naphthenes), which produced by refinery of Sinopec Jinling Petrochemical Corp., Ltd, were used as raw materials. Solvents applied for extractive distillation were selected and researched by the experimental method in order to choose good solvents to isolate isoparaffins or naphthenes from D60 and D40.Four solvents were selected initially under some experiential rules. Then, the experiments of phase equilibrium were done in the apparatus designed by ourselves and the effect of certain single solvent on the relative volatility was studied at given solvent:feed weight ratio. Based on the study of single solvents, the effect of using bianary solvent with different component on the relative volatility and separation results was investigated and compared with above single solvents. At last, the effect of water content on the equilibrium temperature and relative volatility were studied in the paper.The results indicated that sulfolane and a mixture of sulfolane and dimethyl phthalate (1:1) can be provided with favorable result of separation at a solvent: feed weight ratio 5:1. The relative volatility of isoparaffin/naphthene of D60 or D40 is promoted from 0.818 or 0.605 without using any solvent to 1.648 or 1.151 by using sulfolane as solvent, while 1.835 or 2.895 by using mixed solvent of sulfolane and dimethy phthalate.