Fundamental Studies on Well-Defined Oxide Catalysts: from UHV to

Fundamental Studies on Well-Defined Oxide Catalysts: from UHV to Ambient Pressure
Darío J. Stacchiola
Department of Chemistry, Brookhaven National Laboratory, Upton, NY 11973
Low concentration of active sites in the oxide support of catalysts may be blocked by the anchoring of
metal particles. By using a second oxide as a support (host), one can create a multifunctional
configuration in with both metal and oxide active centers exposed to reactants.[1] The natural abundance
of Cu and its catalytic performance for CO oxidation, water-gas shift (WGS) and methanol synthesis have
made it a prime target for catalysis. The Achilles heel of Cu-based catalysts is its deactivation by
complete oxidation to CuO or reduction to Cu,[2] in both cases losing active catalytic Cu+ centers. They
were the first reported to run CO oxidation (CO+1/2O2→CO2) at room temperature, but their lack of
thermal stability at temperatures used on automobile catalytic converters leads to their deactivation. We
show how the incorporation of Ti in a Cu2O film leads to the formation of a stable mixed-metal oxide,
with a Cu+ terminated surface active for CO oxidation.[3] The oxidation of CO during the WGS reaction
(CO+H2O→CO2+H2) occurs in this case under an overall reducing environment. By using a combination
of in-situ techniques combined with theory, we show how the formation of a multifunctional metal-oxide
interface with ceria nanoparticles allows the stabilization of critical intermediates for an efficient
associative reaction mechanism.[4] A similar metal-oxide interface can help to activate copper for the
thermal reduction of CO2. Optimizing the oxide phase and metal-oxide interfaces in a catalyst can
improve substantially their catalytic activity and selectivity.
[1] D Stacchiola, SD Senanayake, P Liu, JA Rodriguez, Chem. Rev. 2013, 113, 4373–4390
[2] AE Baber, F Xu, F Dvorak, K Mudiyanselage, M Soldemo, J Weissenrieder, SD Senanayake, JT Sadowski, JA
Rodriguez, V Matolín, MG White, DJ Stacchiola, J. Am. Chem. Soc. 2013, 135, 16781–16784
[3] AE Baber, X Yang, HY Kim, K Mudiyanselage, M Soldemo, J Weissenrieder, SD Senanayake, A AlMahboob, JT Sadowski, J Evans, JA Rodriguez, P Liu, FM Hoffmann, JG Chen, DJ Stacchiola, Angew. Chem.
Int. Ed. 2014, (DOI: 10.1002/anie.201402435)
[4] K Mudiyanselage, SD Senanayake, L Feria, S Kundu, AE Baber, J Graciani, AB Vidal, S Agnoli, J Evans, R
Chang,S Axnanda, Z Liu, JF Sanz, P Liu, JA Rodriguez, DJ Stacchiola, Angew. Chem. Int. Ed. 2013, 52,
5101–5105
[5] J Graciani, K Mudiyanselage, F Xu, AE Baber, J Evans, SD Senanayake, DJ Stacchiola, P Liu, J Hrbek, J
Fernández-Sanz, JA Rodriguez, Science, 2014, 345, 546-550
El grupo del Dr. Stacchiola ha logrado ensamblar un set de técnicas microscópicas y espectroscópicas
para realizar estudios in-situ de procesos químicos en superficies que está a la vanguardia mundial. Esto
le ha permitido establecer mecanismos moleculares de reacciones catalíticas, analizando la presencia de
especies intermediarias y la dinámica de cambios químicos y morfológicos que se producen en la
superficie de los catalizadores. El Dr. Stacchiola es científico staff en el Brokhaven National Laboratory y
profesor de la Michigan Technological University. Tiene más de 100 publicaciones en el área de ciencia
de superficies relacionada con catálisis, con un alto índice de impacto. Su enfoque es en el estudio de
procesos in-situ, con énfasis en técnicas basada en luz de sincrotrón.
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CONTACTO: Adrian Bonivardi (abonivar@santafe-conciet.gov.ar)