Redispersión dinámica del sitio de cobre a través del atrapamiento de átomos en defectos de zeolita
Stephen C Purdy1, Gregory Collinge2, Junyan Zhang1
1Manufacturing Science Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37830, United States.
Journal of the American Chemical Society
|March 11, 2024
Resumen
Los catalizadores de cobre a base de zeolita se pueden regenerar después de la sinterización mediante un simple tratamiento de aire a alta temperatura. Este proceso de regeneración oxidativa dispersa efectivamente los aglomerados de óxido de cobre en sitios individuales, mejorando la estabilidad y la reutilización del catalizador.
Área de la Ciencia:
- Catálisis heterogénea
- Ciencias de los materiales
- Nanotecnología
Sus antecedentes:
- Los catalizadores de cobre de un solo sitio ofrecen una alta actividad y selectividad, pero sufren desactivación a través de la sinterización en entornos de reducción a alta temperatura.
- Los cambios estructurales irreversibles limitan la aplicación a largo plazo de estos valiosos catalizadores.
Objetivo del estudio:
- Desarrollar una estrategia de regeneración para los catalizadores de cobre de un solo sitio basados en zeolita.
- Investigar los cambios dinámicos de la estructura y del estado de oxidación del cobre en diversas condiciones.
- Comprender el mecanismo de la redispersión y estabilización del cobre dentro de los marcos de la zeolita.
Principales métodos:
- Síntesis de catalizadores de cobre basados en la zeolita (Cu-Zn-Y/deAlBeta).
- Pruebas catalíticas en condiciones de reacción y envejecimiento acelerado.
- Tratamiento oxidativo en el aire a 550 °C para la regeneración.
- Caracterización mediante imágenes, espectroscopia in situ y mediciones de la velocidad catalítica.
- Simulaciones de dinámica molecular desde el principio.
Principales resultados:
- Los aglomerados de óxido de cobre formados después de la reacción se redispersaron con éxito a sitios individuales a través del tratamiento oxidativo.
- El cobre de un solo sitio exhibió cambios dinámicos en el estado de oxidación (Cu2+ a Cu1+ a Cu0) y en la estructura.
- Se identificaron nidos de silanol de zeolita como sitios clave para atrapar y estabilizar el cobre de un solo sitio después de la regeneración.
- La regeneración fue efectiva en presencia y ausencia de promotores de Zn e Y.
Conclusiones:
- Una simple estrategia de regeneración oxidativa a 550 °C en el aire puede restaurar los catalizadores de cobre de un solo sitio después de la sinterización.
- Los nidos de silanol de zeolita juegan un papel crucial en la estabilización de sitios individuales de cobre en condiciones de oxidación.
- Este enfoque mejora significativamente la durabilidad y aplicabilidad de los catalizadores de cobre de un solo lugar.
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