Catalytic functionalities of supported sulfides. VI. The effect of H sub 2 S promotion on the kinetics of indole hydrogenolysis

The kinetics of concurrent indole hydrogenolysis and naphthalene hydrogenation in the presence of varying concentrations of H{sub 2}S were studied in a fixed-bed reactor at 350{degree}C and 35 atm total pressure over a sulfided CoMo/Al{sub 2}O{sub 3} catalyst. Major reaction products from indole hydrogenolysis consisted of o-ethylaniline, ethylcyclohexane, and ethylbenzene, with small amounts of dihydroindole formed in equilibrium with indole. Data were analyzed with Langmuir-Hinshelwood rate equations. It was found that the rate of the first C-N bond-breaking step leading to o-ethylaniline depended on the square root of the H{sub 2}S partial pressure and was inhibited by indole and dihydroindole. Ring hydrogenation reactions were similarly inhibited, but were little affected by H{sub 2}S. The kinetic analyses support the concept that different catalyst sites are involved in the C-N hydrogenolysis and ring hydrogenation reactions. 19 refs.