Degussa Aktiengesellschaft

H.c. Starck Tantalum and Niobium Gmbh

H.c. Starck Gmbh

Elisabeth Droste

Christoph Schnitter

Georg Oenbrink

Thomas Schiffer

Helmut Haas

Ulrich Bartmann

Bernt Krebs

Guido Vollmer

Markus Piepenbrink

The present invention relates to a process for the deoxidation of valve metal primary powders by means of reducing metals and/or metal hydrides, and a process for the production of tantalum powders that are suitable as anode material for electrolytic capacitors.

Method for the production of valve metal powders

The selective epoxidation of cis double bonds of macrocyclic aliphatic hydrocarbons having 8 to 20 ring carbon atoms occurs by a catalytic process. The macrocyclic aliphatic hydrocarbons may optionally contain one or more side chains and in which at least one further trans double bond is simultaneously present. The used catalyst system consists of a cationic phase-transfer catalyst and an anionic polyoxometallate which is a polytungstate or a polymolybdate. Additionally, it comprises one or more elements selected from germanium, tin, lead, arsenic, antimony, bismuth, selenium, tellurium and polonium, and optionally one or more transition metals from group 4 to 12 of the Periodic Table.

Process for the epoxidation of CIS double bonds

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Goslar, Germany

Elisabeth Droste