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Hidrogenación de las especies de formato utilizando hidrógeno atómico en un catalizador modelo Cu

Kotaro Takeyasu^1,2,3, Yasutaka Sawaki⁴, Takumi Imabayashi⁴

¹Faculty of Pure and Applied Sciences, University of Tsukuba, 1-1-1 Tennodai, Tsukuba, Ibaraki 305-8573, Japan.

Journal of the American Chemical Society

|June 28, 2022

Resumen

Este estudio aclara la síntesis de metanol a partir de CO2 en catalizadores de Cu mediante la identificación del dioximetileno adsorbido (H2COOa). Este intermedio se forma mediante la hidrogenación del formato adsorbido (HCOOa) y se descompone, siendo potencialmente el paso determinante de la producción de metanol.

Área de la Ciencia:

Química de las superficies
Catálisis
Mecanismos de reacción

Sus antecedentes:

La síntesis de metanol a partir de la hidrogenación de CO2 en catalizadores de Cu es crucial para la química sostenible.
El mecanismo de reacción preciso, en particular el papel de los intermediarios como el formato adsorbido (HCOOa), sigue sin estar claro.
La detección experimental de productos intermedios durante la hidrogenación de HCOOa es un reto.

Objetivo del estudio:

Para elucidar el mecanismo de reacción de la síntesis de CH3OH a partir de la hidrogenación de CO2 en Cu{111).
Establecer las características cinéticas de los productos intermedios formados por la hidrogenación de HCOOa.
Identificar los intermediarios clave y sus funciones en el ciclo catalítico.

Principales métodos:

Exposición del formato adsorbido (HCOOa) en Cu{111) al hidrógeno atómico a 200-250 K.
Observación de las especies de reacción mediante espectroscopia de absorción por reflexión infrarroja (IRA).
Análisis de la formación y descomposición del producto mediante estudios de desorción programada por temperatura (TPD).
Incorporación de cálculos de la teoría funcional de la densidad (DFT) y datos de la literatura.

Principales resultados:

El dioximetileno adsorbido (H2COOa) fue identificado como un intermediario clave a través de la espectroscopia IRA.
H2COOa se forma al hidrogenarse el HCOOa y se descompone térmicamente alrededor de 250 K.
Se detectaron pequeñas cantidades de formaldehído (HCHO), lo que indica su vía de formación.
Se propone como paso determinante la hidrogenación del bidentato HCOOa a H2COOa.

Conclusiones:

La hidrogenación de HCOOa a H2COOa es un paso crítico en la síntesis de CO2 a metanol en Cu.
El H2COOa es un intermediario inestable que se descompone, lo que influye en la cinética general de la reacción.
El mecanismo propuesto, incluido el paso de determinación de la velocidad, proporciona información sobre la optimización de la síntesis de metanol.

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