Rohm Gmbh

Wolfgang Ruppert

Klaus Langerbeins

Hermann-Josef Siegert

Gerhard Emig

Ruediger Jelitte

Willi Ploesser

Wilheim Gruber

Otto Watzenberger

In the manufacture of isobutyric acid or its precursors or esters by the Koch synthesis from propylene, carbon monoxide, and, optionally, water or an alcohol in liquid hydrogen fluoride, the reaction mixture is maintained at a constant reaction temperature in a heat exchanger using an addition product of at least two of the aforementioned materials, preferably isopropanol, as a coolant.

Method for making isobutyric acid

Methods of improving the yield in the continuous preparation of isobutyric acid from propene, carbon monoxide, and water under pressure in liquid hydrogen fluoride as a Koch catalyst by mixing the propene with excess carbon monoxide, preferably carbon monoxide reintroduced from the process and freed of HF, and introducing the mixture into the reactor.

Continuous method for making isobutyric acid

The invention relates to the stabilization of the activity and/or the reactivation of molybdoheteropoly acid catalysts in vapor-phase oxidations, such as the oxidehydrogenation of isobutyric acid or its lower esters to methacrylic acid or its lower esters, by means of an oxidizing treatment of the catalyst in which compounds of catalyst constituents are added, at temperatures ranging from 200.degree. to 400.degree. C., with an oxygen-containing gas. The inventive activation measures can be carried out either during the catalytic vapor-phase reaction, such as oxihydrogenation in particular, or intermittently to alternate therewith, and optionally also physically separated in part from each other.

Method for the catalytic vapor phase oxydehydrogenation of isobutyric

In the continuous preparation of isobutyric acid by the Koch synthesis from propylene, carbon monoxide, and water or an alcohol in hydrogen fluoride under pressure, the reaction mixture, after reaction, is depressurized, a principal amount of the gaseous components to be removed is separated, the remaining liquid phase is introduced into the middle to upper region of a distillation column in which base temperature is kept above the boiling point of isobutyric acid and the head temperature is kept near the boiling point of hydrogen fluoride, and isobutyric acid is removed as a liquid of high purity from a plate below the entrance of the feed.

Method for regenerating catalysts containing molybdenum, phosphorus, and vanadium in oxidic association and useful for the oxydehydrogenation of isobutyric acid or its lower esters to form methacrylic acid or its lower esters, by oxidizing the spent catalyst with an oxygen containing gas at temperatures from 200.degree. C. to 400.degree. C., suitably intermittently and in alternation with oxydehydrogenation.

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Bickenbach, Germany

Wolfgang Ruppert