Method for separating hydrogen chloride and water from an aqueous hydrogen chloride solution

摘要

The present invention provides a method for efficiently separating hydrogen chloride and water, without adding a third component, from an aqueous hydrogen chloride solution of which separation into components is difficult due to formation of an azeotropic mixture, which method comprises the steps of: providing a hydrogen chloride distillation column and a dehydration column; operating the distillation column under a pressure higher than the pressure of the dehydration column; feeding and distilling an aqueous hydrogen chloride solution having a composition richer in hydrogen chloride than an azeotropic composition when under a pressure equal to the pressure of the distillation column, to the distillation column; recovering hydrogen chloride from the top of the distillation column; feeding and distilling an aqueous hydrogen chloride solution having a composition richer in water than an azeotropic composition when under a pressure equal to the pressure of the dehydration column, to the dehydration column; recovering water from the top of the dehydration column; feeding a part or all of the liquid recovered from the bottom of the distillation column to the dehydration column; and feeding a part or all of the liquid recovered from the bottom of the dehydration column to the distillation column.