Catalytic Activity of Osmium

In the finely divided condition metallic osmium possesses marked catalytic activity. At 40° to 50° C. it causes hydrogen and oxygen to unite with explosive violence. It has proved to be a very effective catalyst in the preparation of ammonia by synthesis from its elements under a pressure of 185 atmospheres and at a temperature of 880° to 1000° C. Osmium obtained by ignition of ammonium chlorosmate in hydrogen, when mixed with certain unsaturated organic substances such as cyclohexene, either alone or diluted with acetone, and exposed to an atmosphere of oxygen, catalytically assists their oxidation. This property is not shared under these conditions by the other platinum metals, although tellurium exhibits a certain degree of activity.