Catalysis by Supported Metal Crystallites from Carbonyl Clusters. I. Catalytic Methanol Synthesis under Mild Conditions over Supported Rhodium, Platinum, and Iridium Crystallites Prepared from Rh, Pt, and Ir Carbonyl Cluster Compounds Deposited on ZnO and MgO

Abstract

Abstract Methanol synthesis by the catalytic hydrogenation of carbon monoxide proceeded under atmospheric pressure and at 150–250 °C over rhodium, platinum and iridium crystallite catalysts, prepared from well-defined Rh, Pt, and Ir carbonyl cluster compounds highly dispersed on ZnO and MgO. The activity and selectivity of methanol formation depended considerably on the kind of metal carbonyl clusters and metal oxides employed as inorganic carriers. The catalysts prepared by the pyrolysis of smaller Rh, Pt, and Ir carbonyl clusters on ZnO, MgO, CaO, and BeO exhibited a higher selectivity of methanol synthesis. A small amount of ethanol was also produced besides methanol in CO–H2 reaction over the pyrolysed catalysts of Rh carbonyl clusters on MgO, CaO, and BeO. Other metal oxides such as SiO2 gel, γ-Al2O3, SnO2, and WO2 were employed for preparation of the dispersed Rh catalysts from carbonyl clusters, which catalysed mainly formation of methane and higher hydrocarbons with negligible selectivity of the oxygenated products under the reaction conditions.