Catalytic properties of metal-carbon systems in the dehydrogenation of ethylbenzene to styrene

Abstract

The catalysts were prepared by dispersing metals (Pt, Pd, Ni, Co) on activated carbon by wetness impregnation and their catalytic activities were studied through the dehydrogenation of ethylbenzene to styrene. It was found that ethylbenzene was activated on the surface of activated carbon and the supported metal played an important role in the dehydrogenation as a vent of hydrogen produced during the reaction, which is so called the "Reverse spillover" phenomenon. From the activities according to the amount of supported metals, Pt and Pd had Volcano curves, while Ni showed a linearly increasing trend with the increase of the metal amount. In the cases of Pt and Pd, their activities were understood through the competition between their hydrogenation ability and hydrogen-ventilating ability. in the case of Ni, the linear dpendence of its activity on increasing metal amount was interpreted due to its relatively low hydrogenation ability. The PAS spectra of Co catalysts indicated that the metals in the metalcarbon system could be reduced by the produced hydrogen besides their roles in the system for the dehydrogenation.