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Soldadura carbotérmica de dos pasos para acceder a Pd₁ atomicamente disperso en una nanorred tridimensional de

Yafei Zhao¹, Huang Zhou¹, Wenxing Chen²

¹Department of Chemistry, Hefei National Laboratory for Physical Sciences at the Microscale, iChEM (Collaborative Innovation Center of Chemistry for Energy Materials) , University of Science and Technology of China , Hefei 230026 , China.

Journal of the American Chemical Society

|June 13, 2019

Resumen

Un nuevo método de soldadura carbotérmica crea paladio dispersado atómicamente en una nanorred 3D de dióxido de zirconio. Este catalizador Pd1@ZrO2 sintetiza eficientemente el indol mediante hidrogenación y condensación con alta selectividad.

Área de la Ciencia:

Ciencias de los materiales
Catálisis
Nanotecnología

Sus antecedentes:

El desarrollo de catalizadores de un solo átomo estables y altamente dispersos es crucial para las transformaciones químicas eficientes.
Las nanoestructuras de dióxido de zirconio (ZrO2) ofrecen propiedades catalíticas únicas, pero a menudo sufren de agregación.
El carbono dopado con nitrógeno (NC) puede estabilizar los sitios metálicos, pero requiere una integración efectiva con soportes inorgánicos.

Objetivo del estudio:

Desarrollar una nueva estrategia de soldadura carbotérmica para la preparación de sitios de paladio (Pd) dispersos atómicamente en una nanorred 3D de ZrO2 (Pd1@ZrO2).
Investigar el mecanismo de formación y el rendimiento catalítico de la nanonet Pd1@ZrO2 en la síntesis de indol.

Principales métodos:

Una estrategia de pirólisis en dos pasos que comienza con el marco metal-orgánico UiO-66-NH2.
Reducción carbotermal y soldadura con argón seguido de oxidación en el aire.
Caracterización mediante diversas técnicas para confirmar la estructura, la dispersión y los defectos.

Principales resultados:

Los sitios Pd dispersos atómicamente (Pd1) se anclaron con éxito en una nanonet 3D ZrO2 a través de la soldadura carbotérmica.
El proceso implicó la transformación de nanocúmulos de carbono N-dopado (NC) y ZrO2, seguido de la gasificación NC y la soldadura con ZrO2.
Los defectos de oxígeno abundantes en la nanorred de ZrO2 facilitaron el atrapamiento de átomos, lo que condujo a Pd1@ZrO2 resistente a la sinterización.
El catalizador exhibió una excelente frecuencia de rotación (1109,2 h-1) y una selectividad del 94% para la síntesis directa de indol.

Conclusiones:

La estrategia de soldadura carbotérmica proporciona un método robusto para crear catalizadores de un solo átomo altamente estables en soportes de nanonet 3D.
La nanonet Pd1@ZrO2 demuestra un potencial significativo como catalizador semihomogéneo para la síntesis orgánica, específicamente para la producción de indol.
La ingeniería de defectos y el mecanismo de captura de átomos mejoran la longevidad y el rendimiento del catalizador.

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