Magnesium addition to Ni spinels and a composite as design strategy of catalysts for ethanol steam reforming

Abstract

Two synthesis strategies were considered, by one side, spinel structures were studied as precursors of Ni based catalysts and by the other side a mixed oxide composite as support in order to achieve the necessary basic characteristics that could minimize carbon formation in ethanol steam reforming reaction (ESR). For this purpose, two spinels families, Ni1-xMgxAl2O4 and Mg1-xNixAl2O4 and a composite Ni/MgO–Al2O3 were successfully synthetized. Catalysts were characterized by XRD, SBET, TPR, XPS, CO2-TPD and evaluated in ESR. The best catalytic activity was observed for Ni0.99Mg0.01Al2O4 and Ni/MgO–Al2O3. These catalysts presented the highest values of H2 selectivity and the least values of CO selectivity with almost zero formation of methane. This excellent behavior was attributed to the higher reducibility and higher amount of available Ni° species at surface with a higher support interaction. Long term experiences were conducted in order to evaluate stability. Both catalysts remained stable with minimum carbon formation.