The reaction of saturated and unsaturated hydrocarbons with the (110)-(1×2) and (111) surfaces of iridium

The dehydrogenation of propane, cyclopropane, propylene, propyne, and allene has been investigated on the reconstructed Ir(110)-(1×2) surface. Annealing adlayers of these hydrocarbons (at low coverages) leads to the formation of surface hydrogen and hydrocarbon fragments of approximate stoichiometry C3H2. The importance of the β′2 adsite of hydrogen on this surface of Ir has been demonstrated further by poisoning studies with hydrogen, CO and surface carbon. The Ir(111) surface was found to dehydrogenate propylene but neither propane nor cyclopropane under the same reaction conditions, indicating a strong effect of surface geometry for the C–H bond activation of alkanes.