Process for obtaining gaseous hydrogen chloride from dilute, aqueous hydrochloric acid

Abstract

Process for the production of gaseous hydrogen chloride by extraction of dilute aqueous hydrochloric acid with amines. (a) The aqueous hydrochloric acid is extracted with an amine or with a mixture of an amine and an inert organic solvent which is immiscible with water and has a lower boiling point than the amine employed, the amines utilized being tertiary alkyl amines, tertiary aryl dialkyl amines, secondary arylalkyl amines, primary alkylaryl amines, or mixtures thereof, which contain 14-32 carbon atoms in the nitrogen-bound side chains, and among these at most one nitrogen-bound methyl group and at least one aliphatic residue containing at least 6 carbon atoms, and wherein the acid constant K.sub.a of the amine is smaller than 10.sup.-3. (b) An inert, water-immiscible organic solvent which has a lower boiling point than the amine employed is added to the extract, unless the solvent has already been added in stage (a). (c) The extract is distilled, the vapors thus-formed are condensed, the water is continuously separated from the two-phase condensate, and the organic phase is returned into the distillation process. (d) After removal of the water, the extract is distilled under reflux at sump temperatures of between 100.degree. and 250.degree. C., and the gaseous hydrogen chloride thus liberated at the head of the column is withdrawn.

Dependencies are inferred from the claim text.