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Suprimir la lixiviación y la sinterización de metales en la reacción de hidroformilación mediante la modulación de la
Zhounan Yu1,2, Shengxin Zhang1,2, Leilei Zhang1
1CAS Key Laboratory of Science and Technology on Applied Catalysis, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, Dalian 116023, China.
Journal of the American Chemical Society
|April 19, 2024
Resumen
Los catalizadores de un solo átomo de Rh (SAC) son prometedores para la hidroformilación, pero sufren de agregación y lixiviación. Este estudio revela que el CO y los aldehídos causan inestabilidad Rh, mientras que los alquenos estabilizan el catalizador durante más de 100 horas.
Área de la Ciencia:
- Catálisis heterogénea
- Ciencias de los materiales
Sus antecedentes:
- La hidroformilación es un proceso industrial importante que se basa en catalizadores homogéneos, lo que plantea desafíos en la separación y la recuperación.
- Los catalizadores monoatómicos heterogéneos (SAC) ofrecen una alta actividad y regioselectividad, pero su estabilidad, en particular la agregación y lixiviación de metales, sigue siendo una preocupación.
Objetivo del estudio:
- Para aclarar el mecanismo de agregación y lixiviación de rodio (Rh) en las SAC de silicalita-1 Rh.
- Identificar los factores que influyen en la estabilidad del SAC durante las reacciones de hidroformilación.
Principales métodos:
- Se investigó la evolución estructural de las SAC de Rh1@silicalite-1 utilizando la espectroscopia de transformación de Fourier de reflexión difusa, la estructura fina de adsorción de rayos X y la microscopia electrónica de transmisión por barrido.
- Se han llevado a cabo estudios cinéticos para comprender los mecanismos de agregación y lixiviación del Rh en diversas condiciones de adsorción (CO, H2, alceno, aldehídos).
Principales resultados:
- La fuerte adsorción de CO y aldehídos, junto con la reducción de Rh3+ por CO/H2, induce la agregación y lixiviación de Rh al debilitar la unión de soporte de Rh.
- Los alquenos contrarrestan la agregación y la lixiviación a través de la adsorción competitiva y promoviendo la desintegración de los racimos de Rh.
- La alta concentración de alquenos estabiliza las SAC de Rh contra la agregación y la lixiviación durante más de 100 horas de funcionamiento.
Conclusiones:
- La estabilidad de las SAC de Rh es críticamente dependiente de las interacciones de adsorbado y del estado de oxidación de Rh.
- Una estrategia que implique una alta concentración de alquenos mejora efectivamente la estabilidad a largo plazo de los SAC Rh en la hidroformilación, abordando los principales desafíos industriales.
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