Optimization of aromatics extraction of naphtha reformate by propylene carbonate/diethylene glycol mixed solvent

Extraction of aromatics from naphtha reformate using a mixed solvent composed of propylene carbonate (PC) and diethylene glycol (DEG) has been considered in this study. Interaction parameters for DEG were obtained experimentally from the equilibrium data for two ternary systems (octane/toluene/DEG and octane/PC/DEG). An experimental program was set up to study the extraction performance of aromatics using a mixed solvent system. On the other hand, a mathematical model was developed and compared with experimental data. Simulation results showed excellent agreement with the experimental results. Furthermore, an optimization model was developed to obtain the optimal extraction conditions, which minimize the operating cost and solvent losses. The optimization variables considered are solvent-to-feed ratio, solvent-to-solvent ratio, and operating temperature. The optimization model is highly nonlinear because of the fact that solvents and naphtha properties were estimated using the UNIFAC model. Optimization results were compared favorably with the experimental results.