Degussa Aktiengesellschaft

Karl-Heinz Mangartz

Jurgen Engel

Otto Isaac

Gerhard Oepen

Rudiger Schirrmacher

Hubert Eickhoff

Hans-Martin Huber

Ralf Godecke

Norbert Seifried

A process is disclosed for the separation of catalyst-free working solution from working solution containing palladium black of the hydrogenation circuit of the anthraquinone process for the production of hydrogen peroxide. The problem addressed was to improve the separation of a catalyst-free working solution from the hydrogenation circuit containing Pd black, which was previously carried out using filter candles, in order to reduce the process costs. This problem is solved by the use of a microfilter operating on the crossflow principle with a filter membrane of ceramic material, more particularly .alpha.-aluminum oxide, or polyolefin with an average pore diameter of 0.1 to 3.0 .mu.m, preferably 0.1 to 1.5 .mu.m, and more preferably 0.5 to 1.5 .mu.m. The crossflow rate is generally 0.5 to 5 m/sec.

Process for the separation of catalyst-free working solution from the

There is provided a process for the recovery of pure hellebrin which comprises extracting a defatted hellebrin extract dissolved in a water-alkanol mixture or water-acetone mixture with a mixture of a lower alkanol or acetone and di-, tri-, or tetrachloromethane (or dichloroethane) evaporating the extraction agent in a vacuum and then heating with ethanol until the deposition of the first hellebrin crystals begins.

Process for the recovery of pure hellebrin

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Rheinfelden, Germany

Karl-Heinz Mangartz