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Hidrogenólisis selectiva de polioles y éteres cíclicos en sitios superficiales bifuncionales en catalizadores de

Mei Chia¹, Yomaira J Pagán-Torres, David Hibbitts

¹Department of Chemical and Biological Engineering, University of Wisconsin-Madison, 1415 Engineering Drive, Madison, Wisconsin 53706, United States.

Journal of the American Chemical Society

|July 9, 2011

Resumen

Un nuevo catalizador de rodio sobre carbono (Rh / C) promovido por óxido de renio rompe selectivamente los enlaces C-O en éteres y polioles cíclicos. Este catalizador bifuncional utiliza sitios ácidos para la apertura de anillos y sitios metálicos para la hidrogenación, cruciales para la conversión de la biomasa.

Área de la Ciencia:

La catálisis heterogénea.
Conversión de la conversión de biomasa.
Química orgánica es la química orgánica.

Sus antecedentes:

Las materias primas derivadas de la biomasa contienen éteres y polioles cíclicos con enlaces C-O recalcitrantes.
La hidrogenólisis selectiva de estos enlaces C-O es esencial para la valorización de la biomasa.
El desarrollo de catalizadores eficientes y selectivos para la escisión de bonos C-O sigue siendo un desafío.

Objetivo del estudio:

Desarrollar un catalizador selectivo para la hidrogenólisis de enlaces secundarios de C-O en compuestos derivados de la biomasa.
Para dilucidar el mecanismo bifuncional que involucra sitios de ácido y metal.
Para entender el papel de la promoción del óxido de renio en el rodio en los catalizadores de carbono.

Principales métodos:

Síntesis y caracterización del catalizador Rh/C promovido por ReO(x).
Desorción programada por temperatura del amoníaco (NH 3 TPD) para cuantificar los sitios ácidos.
Cálculos de la teoría funcional de la densidad (DFT) para investigar los mecanismos de reacción.
Prueba de la selectividad del catalizador en la hidrogenólisis de éteres y polioles cíclicos.

Principales resultados:

El catalizador Rh/C promovido por ReO(x) demostró una alta selectividad para la hidrogenolización de enlaces C-O secundarios.
NH(3) TPD confirmó la presencia de sitios ácidos superficiales con una densidad de 40 μmol g(-1).
Los cálculos de DFT indicaron que los grupos hidroxilo ácidos en el renio facilitan la activación del enlace C-O a través de intermediarios de iones de carbenio.

Conclusiones:

El catalizador funciona a través de un mecanismo bifuncional, que combina la deshidratación y la apertura de anillos catalizados por ácido con la hidrogenación catalizada por metal.
La promoción del óxido de renio mejora la actividad del catalizador Rh/C y la selectividad para la hidrogenólisis C-O.
Este trabajo proporciona conocimientos mecanicistas para diseñar nuevos catalizadores bifuncionales para la valorización de la biomasa.

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