Hopcalite

Hopcalites (also hopcalite or Germanized hopcalite ) is the name for mixed catalysts consist mainly of manganese dioxide and copper (II ) oxide. In addition, they may contain other metal oxides such as cobalt oxides, and silver (I ) oxide. The name Hopcalites derives from the Johns Hopkins University ( " Hop " ) and the University of California ( "Cal" ), where discovered in the course of basic studies on carbon monoxide oxidation during the First World War and in the 1920s, these catalysts were.

Hopcalites catalyze the oxidation of toxic carbon monoxide (CO) to relatively harmless carbon dioxide ( CO2) through (air) oxygen ( O2) at room temperature. That's why they are used in the filtering gas masks and other respiratory protective equipment. The safe side, even when diving air compressors when they are driven like boats with internal combustion engines. In addition, Hopcalite catalyze the oxidation of various organic compounds at high temperature ( 200-500 ° C).

For the preparation of Hopcaliten laboratory and on an industrial scale, various methods are known, as shown here by way of example:

• Physical mixing of the ( finely divided ) metal oxides
• Co-precipitation of the metal oxides from metal salt solutions (see salts)
• Thermal decomposition of mixtures of metal nitrates (see nitrate) and metal carbonates (see carbonate )

Compositions are, for example, 60 % MnO 2 / CuO 40% or 50 % MnO 2 /30% CuO / CoO 15 % and 5% Ag2O.

Although catalysts are used to Hopkalitbasis for decades in practice, many questions remain regarding their mode of action still open. This is due to their complex structure, which makes it difficult to obtain information on the active site and mechanism of catalysis and deactivation.

See also: catalysis, catalyst, heterogeneous catalysis

• Catalyst