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

Abstract

Ni catalysts supported on ZnxMg1xAl2O4 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 ZnxMg1xAl2O4 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.