Ir-193 and Fe-57 Mossbauer characterisation of iridium/iron bimetallic catalysts for methanol synthesis

Fe-Ir/MgO catalysts derived from the [Et4N](2)[Fe2Ir2(CO)(12)] cluster prec ursor, which exhibit a high activity in the synthesis of methanol from CO a nd H-2, were studied by Ir-193 and Fe-57 Mossbauer spectroscopy. The study extends from the precursors via the fresh to the aged catalysts. The presen ce of iridium in the metallic state as well as the presence of trivalent, d ivalent and alloyed iron is detected. The different structural features of catalysts prepared from mixed-metal cluster compounds and from inorganic sa lt precursors are discussed.