Nature of the catalytically active carbonaceous sites for the oxydehydrogenation of ethylbenzene to styrene

Over the past two decades work has appeared in several different laboratories describing a group of catalysts, such as aluminas and various metal phosphates, which are very selective for the oxydehydrogenation of ethylbenzene to styrene. Evidence has accumulated that the active site for these catalysts is actually a carbonaceous layer which is initially deposited on the surface. Carbon itself has shown significant activity and selectivity for this reaction. The history of this development and the various kinds of evidence which support the role of an active carbon overlayer are reviewed.