Cluster Chemistry: Size-Dependent Reactivity Induced by Reverse Spill-Over

In the present work, the CO oxidn. rate on size-selected Pd clusters supported on thin MgO films is investigated in pulsed mol. beam expts. By varying the cluster coverage independent of the cluster size, we were able to change the ratio of direct and diffusion flux (reverse spill-over) of CO onto the cluster catalyst and thus probe the influence of reverse spill-over on the reaction rate for different cluster sizes (Pd8 and Pd30). The exptl. results show that the change in reaction rate as a function of cluster coverage is different for Pd8 and Pd30. In order to explain these findings, the CO flux onto the clusters is modeled utilizing the collection zone model for the given exptl. conditions. The results indicate that, for small clusters (Pd8), the reaction probability of an impinging CO mol. is independent of whether it is supplied by diffusion or direct flux. By contrast, for larger clusters (Pd30) a reduced reaction probability is found for CO supplied by reverse spill-over compared to CO supplied by direct flux. [on SciFinder(R)]     «

In the present work, the CO oxidn. rate on size-selected Pd clusters supported on thin MgO films is investigated in pulsed mol. beam expts. By varying the cluster coverage independent of the cluster size, we were able to change the ratio of direct and diffusion flux (reverse spill-over) of CO onto the cluster catalyst and thus probe the influence of reverse spill-over on the reaction rate for different cluster sizes (Pd8 and Pd30). The exptl. results show that the change in reaction rate as a fu...     »

Oxidation (catalytic, for CO cluster chem. size-dependent reactivity induced by reverse spill-over) Activation energy Diffusion Molecular beams Reactivity (cluster chem. size-dependent reactivity induced by reverse spill-over) Oxidation catalysts Oxidation kinetics (for CO cluster chem. size-dependent reactivity induced by reverse spill-over) Clusters (metal cluster chem. size-dependent reactivity induced by reverse spill-over) Oxidation Oxidation kinetics (surface cluster chem. size-dependent reactivity induced by reverse spill-over) cluster chem size dependent reactivity induced reverse spillover carbon monoxide oxidn palladium cluster magnesia catalyst     «

Oxidation (catalytic, for CO cluster chem. size-dependent reactivity induced by reverse spill-over) Activation energy Diffusion Molecular beams Reactivity (cluster chem. size-dependent reactivity induced by reverse spill-over) Oxidation catalysts Oxidation kinetics (for CO cluster chem. size-dependent reactivity induced by reverse spill-over) Clusters (metal cluster chem. size-dependent reactivity induced by reverse spill-over) Oxidation Oxidation kinetics (surface cluster chem. size-dependent r...     »

CAN 147:331200 67-3 Catalysis, Reaction Kinetics, and Inorganic Reaction Mechanisms Lehrstuhl fuer Physikalische Chemie I, Technische Universitaet Muenchen, Garching, Germany. Journal 0002-7863 1309-48-4 (Magnesia); 7440-05-3D (Palladium); 150385-95-8; 266317-62-8 Role: CAT (Catalyst use), PEP (Physical, engineering or chemical process), PRP (Properties), RCT (Reactant), PROC (Process), USES (Uses), RACT (Reactant or reagent) (cluster chem. size-dependent reactivity induced by reverse spill-over); 630-08-0 (Carbon monoxide) Role: PEP (Physical, engineering or chemical process), PRP (Properties), RCT (Reactant), PROC (Process), RACT (Reactant or reagent) (oxidn. of; cluster chem. size-dependent reactivity induced by reverse spill-over)     «

CAN 147:331200 67-3 Catalysis, Reaction Kinetics, and Inorganic Reaction Mechanisms Lehrstuhl fuer Physikalische Chemie I, Technische Universitaet Muenchen, Garching, Germany. Journal 0002-7863 1309-48-4 (Magnesia); 7440-05-3D (Palladium); 150385-95-8; 266317-62-8 Role: CAT (Catalyst use), PEP (Physical, engineering or chemical process), PRP (Properties), RCT (Reactant), PROC (Process), USES (Uses), RACT (Reactant or reagent) (cluster chem. size-dependent reactivity induced by reverse spill-o...     »