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Control de la catálisis en superficies de la esfera externa: un estudio comparativo de Ti (IV) de sitios únicos
Nicolás A Grosso-Giordano1, Christian Schroeder2, Alexander Okrut1
1Department of Chemical and Biomolecular Engineering , University of California, Berkeley , Berkeley , California 94720 , United States.
Journal of the American Chemical Society
|March 23, 2018
Resumen
El entorno de la esfera externa tiene un impacto significativo en la catálisis de la epoxidación de alquenos. Los arreglos específicos de silanol en soportes cristalinos mejoran las tasas de epoxidación catalizadas por titanio hasta cinco veces.
Área de la Ciencia:
- Catálisis
- Ciencias de los materiales
- Química inorgánica
Sus antecedentes:
- La epoxidación de alqueno es una transformación química crucial.
- El ajuste del entorno catalítico es clave para mejorar la eficiencia de la reacción.
- Los catalizadores de un solo sitio ofrecen un control preciso de los centros activos.
Objetivo del estudio:
- Investigar la influencia del entorno de la esfera exterior en la epoxidación de alquenos.
- Para comparar el rendimiento de TiIV de un solo sitio en soportes amorfos versus cristalinos.
- Elucidar las características estructurales responsables de las mejoras catalíticas.
Principales métodos:
- Injerto de calix[4]areno-TiIV en un solo sitio en silicatos amorfos y cristalinos de zeotipo delaminado (UCB-4).
- Caracterización utilizando espectroscopias de absorción de rayos UV visibles y rayos X para confirmar la esfera interna del TiIV.
- Espectroscopia de RMN de estado sólido 1H para sondear el entorno de la esfera exterior.
Principales resultados:
- Se mantuvo una esfera interna TiIV constante a través de diferentes soportes.
- Los soportes cristalinos UCB-4 presentan silanoles organizados proximalmente dentro de copas de anillo de 12 miembros.
- Estos arreglos específicos de silanol de la esfera externa condujeron a mejoras de velocidad de hasta 5 veces en la epoxidación.
Conclusiones:
- El entorno de la esfera externa juega un papel crítico en la catálisis de la epoxidación de alquenos.
- Las estructuras de silanol ordenadas en soportes cristalinos aumentan significativamente la actividad catalítica.
- Este estudio pone de relieve la importancia de la ingeniería de apoyo para el diseño de catalizadores de un solo sitio.
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