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Sensibilidad estructural de la hidrogenación de alquinol en nanocristales de paladio controlados por forma y tamaño:
Micaela Crespo-Quesada1, Artur Yarulin, Mingshang Jin
1Group of Catalytic Reaction Engineering, Ecole Polytechnique Fédérale de Lausanne, 1015 Lausanne, Switzerland.
Journal of the American Chemical Society
|July 14, 2011
Resumen
Resultados de la reacción de control de la forma y el tamaño del catalizador. Los nanocristales uniformes de paladio revelaron que los sitios planos favorecen la semihidrogenación, mientras que los sitios de borde promueven la sobrehidrogenación, guiando el diseño racional del catalizador.
Área de la Ciencia:
- La catálisis es la catálisis.
- Ciencia de los materiales Ciencia de los materiales.
- Nanotecnología La nanotecnología es la nanotecnología.
Sus antecedentes:
- El rendimiento del catalizador está vinculado a la forma y el tamaño del nanocristal.
- Los diferentes átomos de superficie en los nanocristales exhiben una reactividad variada.
- El diseño racional del catalizador requiere la comprensión de las relaciones estructura-actividad.
Objetivo del estudio:
- Para sintetizar nanocristales uniformes de paladio (Pd) de varias formas.
- Investigar la influencia de la forma y el tamaño del nanocristal en la actividad catalítica y la selectividad.
- Desarrollar un modelo cinético para predecir el rendimiento óptimo del catalizador.
Principales métodos:
- Síntesis en la fase de solución de los nanocristales Pd (cubo, octaedro, cuboctaedro) mediante el uso de poli (pyrrolidona) (PVP).
- Prueba de nanocristales en la hidrogenación de 2-metil-3-butin-2-ol (MBY).
- Modelado cinético utilizando un mecanismo de Langmuir-Hinshelwood de dos sitios.
Principales resultados:
- Se identificaron dos tipos de sitios activos: sitios planos para la semihidrogenación y sitios de borde para la sobrehidrogenación.
- Los sitios del plano mostraron una semihidrogenación preferencial de MBY a 2-metil-3-buten-2-ol (MBE) independientemente de la orientación cristalográfica.
- Se predice que el catalizador óptimo será de 3-5 nanómetros cúbicos para la producción de MBE.
Conclusiones:
- La forma del nanocristal y la coordinación de los átomos superficiales tienen un impacto significativo en la selectividad catalítica.
- Un mecanismo de dos sitios explica la hidrogenación sensible a la estructura observada.
- Este trabajo cierra la brecha entre los estudios de modelos y la catálisis del mundo real para el diseño racional de catalizadores.
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