Cluster-derived Ir-Sn/SiO2 catalysts for the catalytic dehydrogenation of propane: a spectroscopic study

Ir-Sn bimetallic silica-based materials have been prepared via deposition of the molecular organometallic clusters (NEt4)(2)[Ir-4(CO)(10)(SnCl3)(2)] and NEt4[Ir-6(CO)(15)(SnCl3)] or via deposition of Sn organometallic precursor Sn(n-C4H9)(4) onto pre-formed Ir metal particles. These solids possess promising properties, in terms of selectivity, as catalysts for propane dehydrogenation to propene. Detailed CO-adsorption DRIFTS, XANES and EXAFS characterization studies have been performed on these systems in order to compare the structural and electronic evolution of systems in relation to the nature of the Ir-Sn bonds present in the precursor compounds and to propose a structural model of the Ir-Sn species present at the silica surface of the final catalyst.