Partial hydrogenation of benzene-d6 was carried out with Ru catalyst, promotor and H2O system, The reaction scheme, especially for the process of addition of hydrogen, was clarified by analysis of remaining D value in the hydrogenated products. On the Ru catalyst surface, in addition to hydrogenation reaction, a notable reaction also occurrs such as C-D~H exchange reaction between adsorbed substrates, especially olefin and adsorbed hydrogen generated from H2 and H2O. The latter reaction was emphatically observed within the production route of cyclohexene in Zn-promoted catalyst system. The new production route of cyclohexane was clarified. This route is explained as the hydrogenation of cyclohexene with the adsorbed hydrogen regenerated by dehydrogenation of cyclohexene on the catalyst surface. Selectivity of cyclohexene was very increased by Zn-promoted catalyst system. This effect may be attributed to that; (1) on the catalyst surface, Zn compound raises the stability of hydrogenated intermediates, therefore further hydrogenation of the intermediates to cyclohexane is restrained, and (2) Zn compound hinders readsorption of produced cyclohexene to the catalyst surface, therefore hydrogenation of cyclohexene to cyclohexane is also restrained. © 1990, The Chemical Society of Japan. All rights reserved.
