Novel hybrid separation processes based on pervaporation for THF recovery

Design of novel hybrid processes is performed for the industrial recovery of tetrahydrofuran (THF) from two different highly non-ideal mixtures. The novel hybrid processes combine the advantages of batch and/or continuous distillations, extractive distillation, and pervaporation for efficient separation of highly non-ideal mixtures. Pervaporation, used for the final dewatering of the THF, is the last step in the separation technologies and carried out with available industrial technology (Sulzer Chemtech GmbH, Batch pervaporation BP models, PERVAP® 2210 membrane type). It is necessary, however, to design a proper pre-separation process of the mixture to be pervaporated and coordinate its operation with the pervaporation unit. Since methanol is also present in one of the mixtures, its behaviour during pervaporation is also investigated. It shows that since the methanol is able to permeate the membrane, it should be separated in the pre-separation process. The vapour–liquid equilibrium data indicate that with extractive distillation it becomes possible to break the THF—methanol azeotrope and the appropriate application of pervaporation makes the further reduction of the recovery costs possible. The total annual costs of the novel hybrid separation processes range between 10.3 and 54% of that of the old technology based on chemical dewatering. The THF loss decreases to the 7.5 and 17% of that of the old technology and shows that pervaporation is also a powerful tool for the application of the principles of the sustainable development and consumption.