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Mecanismo de la síntesis de etanol a partir de gas de síntesis en el Rh{111)
1Chemistry Department, Brookhaven National Laboratory, Upton, New York 11973, USA.
Journal of the American Chemical Society
|August 26, 2009
Resumen
Los catalizadores basados en Rh son prometedores para la síntesis de etanol a partir del gas de síntesis. Sin embargo, Rh ((111) favorece la producción de metano, con promotores necesarios para mejorar la selectividad y la productividad del etanol.
Área de la Ciencia:
- La catálisis de la catálisis.
- Ciencias de la superficie Ciencias de la superficie.
- Química computacional es la química computacional.
Sus antecedentes:
- La síntesis de etanol a partir del gas de síntesis es crucial para las aplicaciones energéticas.
- Los catalizadores basados en Rh ofrecen una eficiencia única, pero requieren una comprensión mecánica.
- Los desafíos actuales incluyen una baja selectividad y productividad del etanol.
Objetivo del estudio:
- Investigar el mecanismo a nivel molecular de la síntesis de etanol en Rh111) utilizando DFT.
- Identificar los pasos clave que controlan la velocidad de reacción y la selectividad del producto.
- Proporcionar ideas para el diseño de catalizadores mejorados basados en Rh.
Principales métodos:
- Cálculos de la Teoría Funcional de la Densidad (DFT).
- Análisis de las vías de reacción y estados de transición en Rh{111}.
- Evaluación de las etapas elementales de reacción incluyendo la hidrogenación de CO y la formación de enlaces C-C.
Principales resultados:
- La síntesis de etanol se inicia con la formación de formilo, seguido de la hidrogenación y la inserción de CO.
- Rh111) exhibe una baja productividad de etanol y una alta selectividad hacia el metano.
- El paso que limita la velocidad es la hidrogenación de CO a especies de formilo; la selectividad se rige por la formación de metano y el acoplamiento C-C.
Conclusiones:
- La fuerte interacción Rh-CO impide la hidrogenación de CO pero ayuda a romper el enlace C-O para la síntesis de etanol.
- Los promotores son esenciales para suprimir la formación de metano y mejorar la formación de enlaces C-C para un alto rendimiento de etanol.
- Este estudio proporciona una base para el desarrollo de catalizadores avanzados basados en Rh.
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