Hoechst Aktiengesellschaft

Heinrich Muller

Kurt Bodenbenner

Gerhard Muller

The invention provides a process for the regeneration of dilute sulfuric acid containing organic impurities and possibly also inorganic salt in several steps. In the first step, the dilute acid is concentrated by indirect heat exchange with the vapors of the second step, and in the second step it is concentrated by direct heat exchange with a countercurrent mixture of steam and acid vapors coming from a third step. In this third step, the acid discharged from the second step is mixed in direct heat exchange with superheated steam. The regenerated sulfuric acid is separated from this mixture and the remaining steam/vapor mixture is forwarded to the second step. In the case where the dilute acid contains organic substances, an oxidant is added in at least one of these process steps.

Process for regeneration of sulfuric acid

A two step process for concentrating and desalting dilute sulfuric acid including, first indirectly countercurrently contacting and heating the dilute acid with steam from a second step, removing overhead water vapor and withdrawing concentrated acid, and second further concentrating the acid by directly countercurrently contacting and heating the acid with superheated steam, removing overhead steam and additional water vapor, which is used in the first heating step. Acid of a higher concentration is withdrawn and cooled to crystallize and remove salts and the more highly concentrated sulphuric acid recovered.

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Neu Isenburg, Germany

Heinrich Muller