Purification of tetrahydrofuran from its aqueous azeotrope by extractive distillation: Pilot plant studies

• Dehydration of tetrahydrofuran (THF) from its azeotrope is explored.
• Extractive distillation was selected due to advantages that it offers.
• 1,2-Propanediol (PD) and dimethyl sulfoxide (DMSO) were used as entrainer.
• With PD >95% and with DMSO >99% pure THF was obtained using continuous distillation.

Tetrahydrofuran (THF) is an important chemical which is useful in various applications. THF forms an azeotrope with water which is homogeneous and minimum boiling. Several techniques have been used for breaking this azeotrope including membranes, pressure swing distillation and extractive distillation. This work explores the possibility of using extractive distillation for dehydration and purification of tetrahydrofuran. Pilot scale distillation column experiments are presented in batch, semi batch and continuous mode using 1,2-propanediol and dimethyl sulfoxide as the entrainers. Use of dimethyl sulfoxide helps produce greater than 99% pure THF by mass.