Ni-catalysts supported on ZnxMg1−xAl2O4 for ethanol steam reforming: Influence of the substitution for Mg on catalytic activity and stability

Ni catalysts supported on ZnxMg1−xAl2O4 spinel oxide have been prepared by the wet impregnation method with 8 wt.% Ni. The samples were characterized by XRD, BET area, TPR, CO2–TPD, SEM–EDX and TPO and tested in the ethanol steam reforming reaction.The XRD patterns of Ni catalysts supported on ZnxMg1−xAl2O4 with x = 1 or 0.5 revealed a highly crystalline spinel phase (ZnAl2O4 type) and different size particles of NiO. MgAl2O4 with a poorer crystallinity and NiO were observed for the catalyst supported with x = 0. The presence of Mg into the support composition decreased the Ni2+ reducibility and increased the basicity and the specific surface area, allowing a high dispersion of metallic particles and an improved resistance to carbon deposition in the ethanol steam reforming reaction. Under the experimental conditions used in this work, Ni/MgAl2O4 was the most active catalyst but showed deactivation by graphitic carbon deposition.

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► The Zn substitution for Mg decreased the Ni2+ reducibility.
► The Zn substitution for Mg increased basicity and Ni dispersion.
► The strong metal-support interaction and the small Ni particles were crucial in ESR.
► Ni/MgAl2O4 was the most active catalyst.
► Ni/MgAl2O4 showed deactivation by graphitic carbon deposition.