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La cooperatividad y la dinámica aumentan el rendimiento de los catalizadores de reforma seca de NiFe

Sung Min Kim¹, Paula Macarena Abdala¹, Tigran Margossian²

¹Laboratory of Energy Science and Engineering, Department of Mechanical and Process Engineering, ETH Zurich , Leonhardstrasse 21, Zurich 8092, Switzerland.

Journal of the American Chemical Society

|January 10, 2017

Resumen

La adición de hierro a los catalizadores de níquel mejora significativamente el rendimiento del reformado en seco del metano (DRM). Los catalizadores bimetálicos de NiFe convierten los gases de efecto invernadero CO2 y metano en gas de síntesis, mostrando una mejor estabilidad y actividad al prevenir la deposición de carbono.

Área de la Ciencia:

Catálisis
Ciencias de los materiales
Ingeniería Química

Sus antecedentes:

El reformado en seco del metano (DRM) convierte los gases de efecto invernadero (metano y CO2) en gas de síntesis valioso.
El desarrollo de catalizadores estables y activos es crucial para un DRM eficiente.
El papel de los promotores como el hierro en los catalizadores bimetálicos para DRM no se entiende completamente.

Objetivo del estudio:

Investigar el efecto y el papel del hierro (Fe) en los catalizadores bimetálicos níquel-hierro (NiFe) para el DRM.
Para sintetizar y caracterizar los catalizadores de Ni, Fe y NiFe apoyados en MgxAlyOz.
Para aclarar el mecanismo de promoción de Fe en catalizadores de NiFe durante el DRM.

Principales métodos:

Síntesis de catalizadores monometálicos Ni, Fe y bimetálicos NiFe utilizando un precursor similar a la hidrotalcita.
Caracterización mediante difracción de rayos X (XRD), espectroscopia Raman, oxidación programada por temperatura (TPO), microscopía electrónica de transmisión (TEM), operando XRD, espectroscopia de absorción de rayos X (XAS) y espectroscopia de rayos X dispersiva de energía (EDS).
Cálculos basados en la teoría de la densidad funcional (DFT) para complementar los resultados experimentales.

Principales resultados:

El catalizador bimetálico Ni4Fe1 (Ni/Ni + Fe) = 0.8) exhibió la mayor actividad y estabilidad.
Los catalizadores monometálicos de Ni y Fe mostraron una rápida desactivación y baja actividad, respectivamente, principalmente debido a la formación de carbono grafítico en Ni.
El Fe promueve el DRM formando FeO, que reacciona con los depósitos de carbono a través de un mecanismo redox, regenerando la aleación de NiFe y evitando la desactivación.

Conclusiones:

El hierro actúa como un promotor crucial en los catalizadores de NiFe para la reformación seca del metano, mejorando significativamente la estabilidad y la actividad.
El efecto promotor se atribuye a la formación in situ de FeO, que elimina activamente los depósitos de carbono a través de un ciclo redox.
Es probable que el FeO exista como dominios superficiales delgados, lo que garantiza la proximidad de los sitios activos de Ni para la activación eficiente del metano y la eliminación de carbono.

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