The catalytic hydrogenation of benzene over supported metal catalysts.: II. Gas-phase hydrogenation of benzene over copper-on-silica

A study has been made of the kinetics and mechanism of the gas-phase hydrogenation of benzene over a copper-on-silica catalyst in the temperature range from 300 to 450 K and at 130 to 395 kPa total pressure. Attention has been given also to the kinetics of the hydrogenation of the reaction intermediates 1,4-cyclohexadiene and cyclohexene.Two different catalysts were prepared on Shell silica spheres as a support, one according to the Dutch Patent No. 143,139 and the other according to European Patent No. 0006313. Their texture and analytical composition were studied by means of TEM, nitrogen physisorption and capillary condensation, adsorptive decomposition of nitrous oxide, atomic absorption spectrometry and XPS/AES analysis.The catalyst prepared according to European Patent No. 0006313 had a high mechanical strength, a perfect chemical stability and a high sintering resistance. The mean copper particle diameter was 5.5 nm. The other catalyst displayed poor mechanical strength and fragmented during testing.A reaction mechanism is formulated on the analogy of the mechanism proposed for the hydrogenation of benzene over ruthenium [11].The catalytic activity of copper is compared with that of several other transition metals and presented in the form of modified Tanaka-Tamaru plots.