Reverse hydrogen spillover on and hydrogenation of supported metal clusters: insights from computational model studies

Reverse'' spillover of hydrogen from hydroxyl groups of the support onto supported transition metal clusters, forming multiply hydrogenated metal species, is an essential aspect of various catalytic systems which comprise small, highly active transition metal particles on a support with a high surface area. We review and analyze the results of our computational model studies related to reverse hydrogen spillover, interpreting available structural and spectral data for the supported species and examining the relationship between metal-support and metal-hydrogen interactions. On the examples of small clusters of late transition metals, adsorbed in zeolite cavities, we showed with computational model studies that reverse spillover of hydrogen is energetically favorable for late transition metals, except for Au. This preference is crucial for the chemical reactivity of such bifunctional catalytic systems because both functions, of metal species and of acidic sites, are strongly modified, in some cases even suppressed - due to partial oxidation of the metal cluster and the conversion of protons from acidic hydroxyl groups to hydride ligands of the metal moiety. Modeling multiple hydrogen adsorption on metal clusters allowed us to quantify how (i) the support affects the adsorption capacity of the clusters and (ii) structure and oxidation state of the metal moiety changes upon adsorption. In all models of neutral systems we found that the metal atoms are partially positively charged, compensated by a negative charge of the adsorbed hydrogen ligands and of the support. In a case study we demonstrated with calculated thermodynamic parameters how to predict the average hydrogen coverage of the transition metal cluster at a given temperature and hydrogen pressure.     «

Reverse'' spillover of hydrogen from hydroxyl groups of the support onto supported transition metal clusters, forming multiply hydrogenated metal species, is an essential aspect of various catalytic systems which comprise small, highly active transition metal particles on a support with a high surface area. We review and analyze the results of our computational model studies related to reverse hydrogen spillover, interpreting available structural and spectral data for the supported species and e...     »

ISI Document Delivery No.: 919WU Times Cited: 3 Cited Reference Count: 67 Vayssilov, Georgi N. Petrova, Galina P. Shor, Elena A. Ivanova Nasluzov, Vladimir A. Shor, Alexei M. St Petkov, Petko Roesch, Notker Deutsche Forschungsgemeinschaft; Alexander von Humboldt Foundation; Volkswagen Foundation; Fonds der Chemischen Industrie (Germany); Bulgarian National Science Fund [DCVP 02/1, DCVP 02/2]; BeyondEverest; Presidium of the Russian Academy of Sciences This work was supported by Deutsche Forschungsgemeinschaft, Alexander von Humboldt Foundation, Volkswagen Foundation, Fonds der Chemischen Industrie (Germany), and the Bulgarian National Science Fund (Contracts DCVP 02/1 and DCVP 02/2). GNV and PSP are grateful for support by the FP7 project BeyondEverest. The Russian team thanks the Presidium of the Russian Academy of Sciences for financial support (Priority Program 22.51). We also acknowledge generous computing resources at Leibniz Rechenzentrum Munchen. 3 Royal soc chemistry Cambridge     «

ISI Document Delivery No.: 919WU Times Cited: 3 Cited Reference Count: 67 Vayssilov, Georgi N. Petrova, Galina P. Shor, Elena A. Ivanova Nasluzov, Vladimir A. Shor, Alexei M. St Petkov, Petko Roesch, Notker Deutsche Forschungsgemeinschaft; Alexander von Humboldt Foundation; Volkswagen Foundation; Fonds der Chemischen Industrie (Germany); Bulgarian National Science Fund [DCVP 02/1, DCVP 02/2]; BeyondEverest; Presidium of the Russian Academy of Sciences This work was supported by Deutsche Fo...     »