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El papel de la ceria en la deshidrogenación oxidativa en catalizadores de vanadia con soporte
Maria Veronica Ganduglia-Pirovano1, Cristina Popa, Joachim Sauer
1Institute of Chemistry, Humboldt Universität zu Berlin, Unter den Linden 6, 10099 Berlin, Germany. vgp@chemie.hu-berlin.de
Journal of the American Chemical Society
|February 4, 2010
Resumen
Los catalizadores de vanadia/ceria mejoran significativamente la oxidación del metanol a formaldehído. Ceria apoya estabilizar los estados reducidos de vanadia, permitiendo temperaturas de reacción más bajas y una actividad mejorada para esta transformación química crucial.
Área de la Ciencia:
- Ciencia de los materiales Ciencia de los materiales.
- La catálisis de la catálisis.
- Química de las superficies.
Sus antecedentes:
- La deshidrogenación oxidativa es clave para producir formaldehído a partir del metanol.
- Los catalizadores basados en vanadia son conocidos para esta reacción, pero los efectos de apoyo son críticos.
- Ceria (CeO2) es un material de soporte prometedor debido a sus propiedades redox.
Objetivo del estudio:
- Para investigar la influencia del soporte de ceria en la actividad de deshidrogenación oxidativa de vanadia.
- Para dilucidar el mecanismo detrás de la mayor reactividad observada en los sistemas vanadia/ceria.
- Para comparar el rendimiento de vanadia/ceria con vanadia en soportes inertes.
Principales métodos:
- Utilizó catalizadores modelo bien definidos VO{x}/CeO{2}{111}.
- Se empleó desorción programada por temperatura (TPD) para evaluar la reactividad.
- Aplicó cálculos de la teoría funcional de la densidad (DFT) para comprender la energética de superficie.
Principales resultados:
- Los catalizadores de vanadia/ceria exhibieron temperaturas de reacción significativamente más bajas (370 K) en comparación con la ceria pura o la vanadia en sílice.
- Los cálculos de DFT predijeron energías de formación de vacantes de hidrogenación y oxígeno mejoradas para el sistema vanadia/ceria.
- La capacidad de Ceria para estabilizar los estados reducidos de vanadia se identificó como el origen del efecto de soporte.
Conclusiones:
- El apoyo de Ceria juega un papel crucial en la mejora de la deshidrogenación oxidativa del metanol sobre los catalizadores de vanadia.
- La estabilización de las especies de vanadia reducidas por los estados f de ceria es responsable de la mejora de la actividad catalítica.
- Estos hallazgos ofrecen ideas para el diseño de catalizadores avanzados para la producción de formaldehído.
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