Microstructural design of Ni-Fe catalysts for ethanol steam reforming

Abstract

Efficient and stable catalysts for ethanol steam reforming (ESR) are strategic for sustainable hydrogen production. In this study, a rational microstructural architecture of catalysts is investigated by combining nickel and iron active metals, supported on shape-controlled SiO2 (FeNi/SiO2), and adding a protective CeO2 shell layer (FeNi/CS). This designed microstructure exhibits direct impact on the catalytic properties for ESR, as confirmed by detailed characterization. Temperature-programmed reduction (H2-TPR) and X-ray Photoelectron Spectroscopy (XPS) results indicated strong metal–support interactions and oxygen vacancies in the CeO2 shell, which enhanced redox properties. Under ESR conditions at 600 °C, the addition of the ceria shell layer resulted in increased catalytic stability, maintaining 100% ethanol conversion and ∼70% H2 production over 80 h, with minimal carbon deposition (11.7 mgC gcat–1 h–1) as compared to FeNi/SiO2 (20.7 mgC gcat–1 h–1). The enhanced properties achieved for the FeNi/CS sample are attributed to the design of the support and the CeO2 layer, which mitigates metal sintering and maximizes the synergistic effect of the Ni–Fe interaction to effectively hinder coke formation by promoting the gasification of carbon species. These results confirm that the bimetallic active species, engineered with a core–shell design having an active layer over a stable support is a promising strategy to enhance the durability and activity of non-noble metal catalysts for ESR applications.