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Datos técnicos
Revista | Journal of Physical Chemistry C |
---|---|
Año | 2011 |
Volumen | 115 |
Páginas | 7399-7410 |
Internacional | Sí |
Periodic Density Functional Theory Study of VO(n) Species Supported on the CeO(2)(111) Surface
Autores:Cristina Popa , María Verónica Ganduglia Pirovano, J. Sauer
Grupos de investigación:Catálisis Teórica y Modelización
We model monomeric vanadia adspecies on the CeO(2)(111) surface of
composition VO(n)center dot Ce(12)O(24) (n = -1, 0, ... , 4) using the
DFT+U approach and statistical thermodynamics. At low oxygen pressure
(10(-9) atm), VO(4) is the most stable species below 400 K; in the
400-900 K range; VO(2) is stable; and above 900 K, VO becomes stable. In
all of these systems, vanadium is stabilized in the +5 oxidation state.
Using the energies of hydrogenation and oxygen vacancy formation as
reactivity descriptors, we predict an enhanced reactivity of the
vanadia/ceria system in Mars-van Krevelen-type oxidation reactions. At
the orgin of this support effect is the ability of ceria to stabilize
reduced states by accommodating electrons in localized f states. We also
calculate the frequencies of the normal vibrat onal modes of the
supported VO(n) species and their infrared intensity.
Palabras clave:VANADIUM-OXIDE CATALYSTS, FORMALDEHYDE, AUGMENTED-WAVE METHOD, TOTAL-ENERGY CALCULATIONS, OXIDATIVE DEHYDROGENATION, RUTILE TIO2(110), METAL-OXIDE, BASIS-SET, METHANOL, PROPANE