| AVS 55th International Symposium & Exhibition | |
| Surface Science | Thursday Sessions |
| Session SS2+NC-ThM |
| Session: | Catalysis on Nanoclusters |
| Presenter: | H.L. Abbott, Fritz Haber Institute of the Max Planck Society, Germany |
| Authors: | H.L. Abbott, Fritz Haber Institute of the Max Planck Society, Germany A. Uhl, Fritz Haber Institute of the Max Planck Society, Germany M. Baron, Fritz Haber Institute of the Max Planck Society, Germany D.J. Stacchiola, Fritz Haber Institute of the Max Planck Society, Germany S.K. Shaikhutdinov, Fritz Haber Institute of the Max Planck Society, Germany H.-J. Freund, Fritz Haber Institute of the Max Planck Society, Germany |
| Correspondent: | Click to Email |
Vanadia particles and monolayer or submonolayer coverage vanadia films supported on metal oxide surfaces have shown high activity for the selective oxidation of alcohols. In particular, methanol oxidative dehydrogenation to formaldehyde occurs readily on ceria-supported vanadia. Although support and coverage effects are known to be important for this reaction, questions remain about the relationship between the structure and the reactivity. Here, a well-defined model system, consisting of vanadia nanoparticles deposited on thin ceria films, has been employed. X-ray photoelectron spectroscopy (XPS), scanning tunneling microscopy (STM), infrared reflection absorption spectroscopy (IRAS), and temperature programmed reaction (TPR) were used to characterize the VOx/CeO2 model system. XPS measurements indicated that the oxidation state of the vanadium atoms increases with decreasing coverage. Under low coverage conditions, STM images revealed the presence of isolated vanadia species. Vanadyl stretching vibrations detected by IRAS vary between 1000 and 1050 cm-1, depending on the coverage and the annealing temperature. Two TPR peaks, corresponding to the selective oxidation of CH3OH on VOx, were observed, including a new low temperature peak at ~350 K that is believed to correlate with isolated species.