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Catalizador de conjunto de Rh totalmente disperso para mejorar la actividad a baja temperatura

Hojin Jeong¹, Geonhee Lee², Beom-Sik Kim¹

¹Department of Chemical and Biomolecular Engineering , Korea Advanced Institute of Science and Technology , Daejeon 34141 , South Korea.

Journal of the American Chemical Society

|July 6, 2018

Resumen

Los investigadores desarrollaron catalizadores de rodio (Rh) altamente dispersos que superan a los catalizadores de un solo átomo (SAC) para las reacciones de oxidación a baja temperatura. Estos catalizadores muestran una mayor eficiencia y actividad atómica, crucial para las aplicaciones industriales.

Área de la Ciencia:

Catálisis heterogénea
Ciencias de los materiales
Química de las superficies

Sus antecedentes:

Los catalizadores de metales preciosos son vitales pero costosos; minimizar su uso es un objetivo clave.
Los catalizadores de un solo átomo (SAC) ofrecen la máxima eficiencia atómica, pero carecen de sitios de conjunto para ciertas reacciones.
Las reacciones que requieren múltiples átomos de metales adyacentes no pueden ser catalizadas por SAC.

Objetivo del estudio:

Desarrollar un catalizador de rodio (Rh) altamente disperso con sitios de ensamblaje.
Evaluar el rendimiento catalítico del nuevo catalizador Rh en comparación con los SAC.
Comprender el mecanismo de formación de catalizadores y su impacto en la actividad.

Principales métodos:

Tratamiento hidrotermal del 2 por ciento en peso de Rh/CeO2 a 750 °C durante 25 horas.
Caracterización de la dispersión del catalizador y el estado de agregación del átomo Rh (ENS vs. SAC).
Prueba de la actividad catalítica en la oxidación a baja temperatura de CO, C3H6 y C3H8, incluidas las reacciones simultáneas.

Principales resultados:

Se obtiene casi el 100% de dispersión con átomos Rh no aislados (ENS) después del tratamiento hidrotermal.
Los catalizadores ENS catalizaban efectivamente la oxidación C3H6 y C3H8, a diferencia de los SAC Rh.
Los catalizadores ENS mostraron temperaturas de apagado significativamente más bajas (T20) en la oxidación simultánea de CO, C3H6 y C3H8 en comparación con los SAC (100 °C frente a 180 °C para la oxidación de CO).

Conclusiones:

El catalizador ENS Rh desarrollado exhibe una actividad de oxidación superior a baja temperatura en comparación con los SAC.
El tratamiento hidrotermal facilita el desprendimiento del átomo Rh y evita la reagregación a través de los grupos hidroxilo superficiales.
Este catalizador ENS totalmente disperso ofrece una alta eficiencia atómica y un rendimiento catalítico mejorado para reacciones específicas.

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