OXYDEHYDROGENATION OF ETHYLBENZENE TO STYRENE CATALYZED BY GRAPHITES AND ACTIVATED CARBONS

The catalytic activity and selectivity of carbon materials (graphites and activated carbons) in the oxidative dehydrogenation of ethylbenzene have been studied as a function of time on stream. The changes in activity and selectivity are explained as due to the formation of carbonaceous deposits on the sample surfaces. The surface area, the porous structure, the presence of surface groups, and the reactivity in air of the different carbon samples have been determined and related to their catalytic performance. The ability of hydrogen present at the carbon surfaces to be exchanged with deuterium atoms of deuterated benzene have been measured before and after the use as catalyst. The chemical nature of the surface coke is found to be conditioned by that of the carbon substrate. The selectivity for styrene is concluded to be associated with the capacity to form surface groups with labile hydrogen atoms.