Abstract: An improved process for the preparation of cyanamide or a cyanamide-containing gas mixture by passing urea and/or urea decomposition products over a catalyst at a temperature in the range of between about 200.degree. C. and 600.degree. C. A porous catalyst is utilized which has an intracrystalline pore diameter of at most 8 A, whereby a high conversion to cyanamide is obtained and the formation of melamine by-products is substantially reduced.

Abstract: A process for the reactivation of spent tellurium-containing oxidic catalysts (suitable for oxidation, ammoxidation and/or oxidative dehydrogenation of olefines), wherein a solid particulate tellurium compound especially tellurium oxide compound, is mixed with the spent catalyst to raise the tellurium content thereof to a value of between 90% and 500% of the original catalyst content.

Abstract: An improved process for the preparation of cyclohexanone from benzene. Benzene is hydrogenated in a gaseous phase in a hydrogenation zone to form cyclohexane; cyclohexane is oxidized in a liquid phase to form a mixture containing cyclohexanol and cyclohexanone; and cyclohexanone is separated from this mixture and is catalytically dehydrogenated to form cyclohexanone and a hydrogen containing gas. The resulting hydrogen containing gas is introduced into a washing zone wherein it is washed with cyclohexane or benzene and the hydrogen gas thus purified is fed into the hydrogenation zone.