Oxidation of cyclopropane with coadsorbed oxygen on Pt(111)

Coadsorption of cyclopropane with either atomic oxygen or molecular oxygen on the Pt(111) surface results primarily in oxidation to carbon dioxide and water. With coadsorbed atomic oxygen, sequential hydrogen abstraction occurs at 265 and 315 K, followed by oxidation of the remaining hydrogen depleted species. With coadsorbed molecular oxygen, a low temperature hydrogen abstraction reaction lakes place at 210 K. The kinetically limited oxidation of the remaining surface intermediate results in simultaneous high temperature desorption of water and carbon dioxide at 380-410 K. Low temperature hydrogen abstraction is believed to be caused by cyclopropane reaction with the coadsorbed molecular oxygen or with the unaccommodated oxygen atoms formed during molecular oxygen dissociation. On the clean Pt(111) surface cyclopropane desorbs at 145 K, with a small fraction dissociating to form hydrogen, leaving a small amount of carbon residue on the surface. Cyclopropane coadsorbs nondissociatively with atomic oxygen. Coadsorbed hydrogen inhibits dehydrogenation but does not result in hydrogenation or hydrogenolysis. (C) 1997 Elsevier Science B.V.