Separation of isobutanol/water mixtures by hybrid distillation-pervaporation process: Modeling, simulation and economic comparison

Hybrid separation processes based on the membrane processes are becoming more important in practice to overcome the thermodynamic limitations of the conventional separation processes as well as to develop more sustainable and economic processes. This study focuses on the use of the hybrid distillation-pervaporation process for the separation of isobutanol/water mixtures. For engineering design of the hybrid processes, reliable modeling and simulation of the process is indispensable. For the simulation of different configurations of the hybrid processes with Aspen Plus software (Aspen Tech), a mathematical model was developed for the pervaporation process based on the solution-diffusion mechanism using the Flory-Huggins and UNIFAC thermodynamic models and Lee's equation. The simulation was performed for the separation of isobutanol/water mixtures with various isobutanol feed concentrations (5, 7, and 15 Wowt.). It was found that for both single-phase and two-phase feed solutions, the hybrid hydrophobic-hydrophilic pervaporation process was the most economical configuration to reach the desired product purity. For the hybrid hydrophobic-hydrophilic pervaporation process with feed concentrations of 5, 7 and 15 %wt., the total annual cost was 62.9 %, 58.7 %, and 58.4 %, respectively, lower than the distillation process. Furthermore, by increasing the feed concentration, the membrane area required for the pervaporation-based hybrid process enhanced.