SMSI effect in some reducible oxides including niobia

摘要: Abstract Niobia is a typical SMSI oxide. High temperature reduction (HTR) exerts reversible suppression of H2 chemisorption on Nb2O5-supported or Nb2O5-promoted Rh Pd catalysts. The activities hydrogenolysis hydrocarbons (a structure-sensitive reaction) are suppressed severely after HTR and those hydrogenation-dehydrogenation structure-insensitive suffer only mild suppression. extent RhNb2O5 interaction depends strongly the preparation conditions, i.e., Nb/Rh atomic ratio, impregnation procedures calcination temperature. A single phase RhNbO4 supported SiO2 similar compounds were prepared successfully, their structural changes during studied extensively. These systems can be assumed to good model for SMSI. effect was compared with several catalytic reactions which supposed structure-sensitive. Usually, more less by an ensemble at state, but enhancement found selective hydrogenation carbonyl group hydroformylation ethylene probably ligand due surface decoration. Recently, role ZnO investigated methanol synthesis over Cu/ZnO/Al2O3 catalysts combination oxygen coverage measurements catalysis, EDX (Energy-dispersive X-ray spectroscopy) observations XPS studies. They gave evidence decoration Cu species, leading formation new active sites, tentatively expressed as Cu+OZn. fact that does not necessarily exert catalysis will presented review paper our group.