Kinetics and mechanism of diphenylamine synthesis by the condensation of aniline with oxygen-containing compounds

The condensation of aniline and cyclohexanol (cyclohexanone) yielding intermediates and the subsequent dehydrogenation of these intermediates into diphenylamine have been studied. The mechanism of diphenylamine synthesis is substantiated. The kinetics of diphenylamine synthesis from aniline and cyclohexanol over a NiSnMg catalyst has been studied. A kinetic model in terms of the conversion of strongly chemisorbed species has been developed. The rate constants of diphenylamine synthesis at 260–300°C have been determined, which are consistent with the observed regularities. The kinetic model can be used in the determination of optimal synthetic conditions and in the design of a reactor for diphenylamine synthesis from aniline and cyclohexanol. Conditions have been found under which diphenylamine synthesis occurs at a high rate of up to 1 kg/(1h), with high selectivity, and with a high yield of up to 95%.