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Mecanismo de reacción dependiente del sitio activo sobre el catalizador Ru/CeO2 hacia la metanación de CO2
Fei Wang1, Shan He1, Hao Chen1
1State Key Laboratory of Chemical Resource Engineering, Beijing University of Chemical Technology , Beijing 100029, P. R. China.
Journal of the American Chemical Society
|May 3, 2016
Resumen
Las vacantes de oxígeno en la cerea (CeO2) son sitios activos cruciales para la metanación del CO2, promoviendo una vía de formato y reduciendo el paso determinante de la velocidad.
Área de la Ciencia:
- Catálisis heterogénea
- Ciencias de la superficie
- Química de los materiales
Sus antecedentes:
- Las vacantes de oxígeno son defectos clave en las superficies de óxido metálico, que actúan como sitios reactivos en procesos catalíticos.
- Comprender el papel del sitio activo es crucial para optimizar las reacciones catalíticas como la metanación de CO2.
Objetivo del estudio:
- Investigar el mecanismo activo dependiente del sitio de la metanación de CO2 sobre los catalizadores Ru/CeO2 y Ru/α-Al2O3.
- Elucidar el papel de las vacantes de oxígeno en el CeO2 durante el proceso catalítico utilizando espectroscopia operando.
Principales métodos:
- Operando espectroscopia XANES, IR y Raman para estudiar la evolución del catalizador en condiciones de reacción.
- Espectroscopia infrarroja DRIFT in situ con análisis cinético transitorio de isótopos en estado estacionario (SSITKA) para determinar las vías de reacción.
- Evaluación de la actividad catalítica y análisis de la reacción oscilante.
Principales resultados:
- Ru/CeO2 con vacíos de oxígeno facilita la metanización de CO2 a través de una vía de formato, siendo la disociación de formato el paso determinante.
- Ru/α-Al2O3 sin vacíos de oxígeno promueve la metanación de CO2 a través de una ruta de CO en la superficie de Ru.
- Las vacantes de oxígeno reducen significativamente la temperatura de activación del paso que determina la velocidad (125 °C frente a 250 °C).
Conclusiones:
- El mecanismo catalítico para la metanización de CO2 depende del sitio activo, específicamente de la presencia o ausencia de vacíos de oxígeno.
- Las vacantes de oxígeno en CeO2 actúan como sitios catalíticos cruciales, mejorando la eficiencia de la conversión de CO2 a temperaturas más bajas.
- Este estudio proporciona una comprensión completa del mecanismo de reacción dependiente del sitio activo en la metanización de CO2.
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