The patent badge is an abbreviated version of the USPTO patent document. The patent badge does contain a link to the full patent document.
The patent badge is an abbreviated version of the USPTO patent document. The patent badge covers the following: Patent number, Date patent was issued, Date patent was filed, Title of the patent, Applicant, Inventor, Assignee, Attorney firm, Primary examiner, Assistant examiner, CPCs, and Abstract. The patent badge does contain a link to the full patent document (in Adobe Acrobat format, aka pdf). To download or print any patent click here.
Patent No.:
Date of Patent:
Sep. 15, 1992
Filed:
Aug. 02, 1991
Hoechst Aktiengesellschaft, Frankfurt am Maiin, DE;
Abstract
In a continuous process for the preparation of phosphorous acid with simultaneous production of hydrochloric acid, a reaction zone is provided which is in open communication with a first scrubbing zone. A portion of the reaction product is recycled from the bottom of the reaction zone into the top of the scrubbing zone and phosphorous acid is removed from the circulation. Hydrogen chloride gas escaping from the top of the first scrubbing zone is brought into contact, in a cooled, second scrubbing zone, with an overstoichiometric amount of water. Hydrochloric acid is obtained which is passed as starting material into the reaction zone or into the top of the first scrubbing zone. The external cooling of the second scrubbing zone is controlled such that the temperature in the reaction zone is kept constant at a desired value between 90.degree. and 130.degree. C. without adding any external cooling or heating energy. Pure hydrochloric acid is recovered in an absorption zone.