Influence of triphenylphosphine on the activity of heterogeneous iridium,rhodium and platinum containing catalysts for the dehydrogenation of saturated hydrocarbons

A series of heterogeneous iridium containing catalysts was synthesized by the incipient wetness method. The support material was silica gel. The heterogeneous catalysts were able to dehydrogenate isopentane to isopentene with very high activities and selectivities. The use of external additives (e.g. PPh₃) in case of the heterogenized iridium complex IrH(CO)(PPh₃)₃ increased the conversion of isopentane up to 30%. Such a conversion rate has been predicted by model calculations of the thermodynamic equilibrium of the dehydrogenation reaction of isopentane.