Simulation and environmental evaluation of process design: Distillation vs. hybrid distillation-pervaporation for methanol/tetrahydrofuran separation

Separation processes are among the most energy-intensive stages in the chemical industry, and the evaluation and minimization of environmental impacts is part of the challenges faced by environmental engineering. Pressure swing distillation is a commonly used technique for separation of the mixture methanol/ tetrahydrofuran (THF); the separation is not feasible with conventional distillation due to the presence of an azeotrope. In this work, the design of a hybrid process consisting of distillation and pervaporation is elaborated as an alternative for the separation and evaluated from a technical and an environmental point of view. Three different compositions of the feed stream are considered: 25, 50 and 75 wt% methanol in THF and the simulation of pressure swing distillation and the hybrid process allows comparison of the energy requirements. In addition, the effect of the membrane performance on the purity of the products and the energy demand were studied. Life cycle assessment (LCA) was used to evaluate the environmental impact of both alternatives compared to incineration. From the LCA, it was observed that the hybrid process produces the lowest impact, indicating that solvent recovery is a key issue to minimize the environmental burdens. Thus, integration of membrane technology in a hybrid configuration should be considered in the design and development of more environmentally friendly processes.