Dynamic controls of an extractive distillation (ED) process and a partially heat-integrated pressure-swing distillation (PHIPSD) process for separating a mixture of 50 mol % ethanol and 50 mol % tetrahydrofuran are investigated. Comparisons between the control structures of the two distillation processes are made. The results show that PHIPSD has advantages of economic savings and control compared with the ED process. In addition, some control structures of PHIPSD for feed streams with different composition and some comparisons between the performances of the control structures are also studied. It is concluded that the feed composition mainly impacts the dynamic control structures of PHIPSD through the different combinations of auxiliary heat exchanger and that a composition controller can improve the control performances.

The mixture of n-heptane and isobutanol creates a minimum-boiling azeotrope under atmospheric conditions. Extractive distillation was used for separating n-heptane and isobutanol. A sequential iterative optimization procedure optimized the steady state extractive distillation process to obtain a minimal total annual cost (TAC). The dynamic control of the optimal extractive distillation process showed poor controllability. It was found that the dynamic control performance could be improved if the solvent flow rate was increased properly with a small increase in TAC. Hence, the choice of the optimal extractive distillation process for separating a binary azeotropic mixture should be considered from the perspectives of both TAC and the dynamic control performance.

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The liquid−liquid equilibrium data of the two ternary systems of n-propyl acetate + n-propanol + 1-butyl-3-methylimidazolium hydrogensulfate and isopropyl acetate + isopropyl alcohol +1-butyl-3-methylimidazolium hydrogensulfate were measured at 298.15 K and 318.15 K and under atmospheric pressure in this work. The extraction effect of ionic liquids was discussed by comparing the values of the distribution coefficient and separation factor. The influence of temperature on the liquid−liquid equilibrium data was discussed. The binary interaction parameters of the nonrandom two-liquid and universal quasichemical models were obtained by regressing the experimental data.