Reaction network of indole hydrodenitrogenation over NiMoS/gamma-Al2O3 catalysts

The reaction network of indole hydrodenitrogenation (HDN) was investigated over gamma-Al2O3 supported NiMo sulfide catalysts in an effort to acquire a fundamental understanding of the different reaction pathways in the mechan ism. Experiments were performed primarily at 1000 psig, using a wide range of temperatures and feed concentrations. The effect of H2S on different rea ction Steps of the network was also investigated. Two major pathways were p roposed to account for the formation of ethylcyclohexane (ECH) and ethylben zene (EB) which are the two main HDN products from indole. One route occurs from the hydrogenolysis of indoline to o-ethylaniline (OEA) and the other from the hydrogenation of indoline to octahydro-indole. Also included in th e proposed mechanism is a secondary route from o-ethylcyclohexylamine (OECH A) to ethylcyclohexene (ECHE), that occurs through a nucleophilic substitut ion reaction. The product distribution was a strong function of temperature and H2S concentration. H2S enhanced the hydrogenolysis reactions but inhib ited the hydrogenation reactions. (C) 2000 Elsevier Science B.V. All rights reserved.