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Oxidación preferencial de CO en hidrógeno: reactividad de las nanopartículas del núcleo
Anand Udaykumar Nilekar1, Selim Alayoglu, Bryan Eichhorn
1Department of Chemical and Biological Engineering, University of Wisconsin-Madison, Madison, Wisconsin 53706, USA.
Journal of the American Chemical Society
|May 13, 2010
Resumen
Diseñamos nuevos catalizadores de nanopartículas (NP) de núcleo con una actividad mejorada para la oxidación preferencial de CO (PROX) en hidrógeno. Los NP con núcleo de Ru@Pt mostraron el mayor rendimiento, demostrando una eficiente oxidación de CO a bajas temperaturas.
Área de la Ciencia:
- Ciencia de los materiales Ciencia de los materiales.
- La catálisis es la catálisis.
- Nanotecnología La nanotecnología es la nanotecnología.
Sus antecedentes:
- El desarrollo de catalizadores eficientes para la oxidación preferencial de CO (PROX) en hidrógeno es crucial para las aplicaciones de celdas de combustible.
- Las nanopartículas de núcleo ofrecen propiedades catalíticas sintonizables mediante el control de los efectos de interfaz.
Objetivo del estudio:
- Para diseñar, sintetizar y caracterizar nuevos catalizadores de nanopartículas (NP) en el núcleo de M@Pt.
- Para investigar su rendimiento catalítico para las reacciones PROX.
- Para aclarar los mecanismos fundamentales que rigen su reactividad utilizando la Teoría Funcional de Densidad (DFT).
Principales métodos:
- Los primeros principios guiaron el diseño y la síntesis de las NP del núcleo de M@Pt (M = Ru, Rh, Ir, Pd, Au).
- Caracterización mediante difracción de rayos X, FTIR, HRTEM y reacción programada por temperatura.
- Evaluación de la actividad catalítica y la selectividad de PROX.
- Estudios mecanicistas utilizando cálculos de DFT.
Principales resultados:
- NPs de núcleo-capa M@Pt sintetizados con un grosor de capa Pt controlado (~1-2 monocapas).
- Se observó una mejora significativa de la actividad y la selectividad de PROX para varios NP M@Pt en comparación con las nanoaleaciones monometálicas y bimetálicas.
- Los NP de núcleo de Ru@Pt demostraron la mayor actividad, logrando una oxidación completa de CO a 30°C.
- Los estudios de DFT revelaron que la actividad aumentada proviene de los sitios Pt libres de CO disponibles para la activación de O2 y una ruta de oxidación de CO mediada por hidrógeno distinta.
Conclusiones:
- Los NP de núcleo M@Pt representan una estrategia prometedora para el diseño de catalizadores PROX altamente activos y selectivos con contenido reducido de platino.
- El metal del núcleo influye significativamente en el rendimiento catalítico de la cáscara Pt.
- Comprender el mecanismo de reacción proporciona información para el futuro desarrollo de catalizadores.
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