Ni–Co Bimetallic Catalysts for Hydrogen Production by Steam Reforming Ethanol

Abstract

Ni–Co catalysts supported on MgAl2O4–CeO2 were prepared by the sol–gel method. The solids were calcined under a reducing atmosphere to obtain Ni and/or Co active sites. The influence of the cobalt content (1, 3 and 5% w/w) was studied on bimetallic catalysts containing 8% w/w of Ni. The catalysts were characterized by TG, FTIR, SBET, AAS, XRD, TPR, TEM, EELS, EFTEM, TPO and SEM. XRD patterns of the reduced samples did not reveal the presence of Ni nor Co, nor the possible formation of a metallic alloy, which suggests that metallic crystallite sizes are smaller than the detection limit of the technique (5 nm). The catalysts were evaluated in the ethanol steam reforming reaction at 650 °C for 7 h. The results showed that the catalytic activity and the H2 selectivity are favored in bimetallic catalysts. The main reaction products were H2, CO2, CO and, to a lesser amount, CH4, being the hydrogen selectivity being greater than 80%. The best behavior in terms of the activity, stability and tolerance to carbon deposition was observed in Co3Ni/MC system. These results suggest the existence of an optimal Co/Ni ratio in the sample whit 3 wt% Co and 8 wt% Ni.