The Oxide and Sulfide Catalysts of Transition Metals

Rhenium Sulfides and Selenides.208 209 These catalysts are characterized by their outstanding resistance to poisoning and minimal tendency to cause the hydrogenolysis of carbon-sulfur bonds than the base metal sulfides. Rhenium heptasulfide is easily prepared from boiling 6M hydrochloric acid solutions of perrhenate with hydrogen sulfide. It has been noted that occasional exposure of the dried, powdered catalyst to the atmosphere is not deleterious. 

7 THE OXIDE AND SULFIDE CATALYSTS OF TRANSITION METALS OTHER THAN RHENIUM 

The sulfides of the platinum metals have been found to be active at lower temperatures than required for the base metal sulfides. They are insensitive to poisons and have proved particularly useful for hydrogenations in the presence of impurities, for the hydrogenation of sulfur-containing compounds, and for selective hydrogenation 

Molybdenum Oxides. Molybdenum oxide catalysts are prepared by the addition of hydrochloric acid to an ammoniacal solution of molybdic acid or ammonium molybdate. By heating to 400-500°C the molybdate is decomposed to the oxide.216 M0O3 is reduced to Mo02 in a stream of hydrogen at 300-400°C. 

Molybdenum Sulfides.217 M0S3 to a solution of 100 g (0.081 mol) of ammonium molybdate( VI), (NH4)6Mo7024 4H20, dissolved in 300 ml of distilled water, is added 

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