Oxidation of cyclohexylamine by air to its oxime

The oxidation of cyclohexylamine was studied over tungsten, molybdenum and vanadium oxides containing catalysts supported on silica, gamma-alumina or hydrotalcite in the temperature range 170 degrees C-230 degrees C. Dependin g on the catalyst and reaction conditions, the main products of the reactio n are cyclohexanone oxime, cyclohexylidenecyclohexylamine or cyclohexanone. About 70% selectivity of cyclohexanone oxime formation at about 20% conver sion of cyclohexylamine is obtained over tungsten catalysts. The activity o f the tested catalysts usually passes through a maximum and, then, graduall y decreases with time on stream. The deactivation of the catalyst is caused by the formation of tar products on the catalyst surface. The mechanism of oxidation involves formation of oxygen species on the catalyst surface whi ch oxidizes cyclohexylamine. (C) 2000 Elsevier Science B.V. All rights rese rved.