Oxidative dehydrogenation of ethane over NiO-CeO2 mixed oxides catalysts

In this paper we present the synthesis, characterization and catalytic behaviour in the oxidative dehydrogenation of ethane of NiO-CeO2 mixed oxides. The addition of cerium oxide to NiO strongly modifies its catalytic performance, although the changes in the catalytic behaviour depend on the catalyst composition. The incorporation of low amounts of cerium oxide to NiO multiplies the productivity to ethylene in the oxidative dehydrogenation of ethane by a factor of ca. 7, which is the result of an increase in both catalytic activity and selectivity to ethylene. The enhanced activity has been related to the remarkable increase of the surface area of catalyst and the low crystal sizes of NiO that takes place when a tiny amount of cerium oxide is incorporated to the NiO. The higher selectivity to ethylene has been related to the modification of the nature of Ni-O species, which implies a lower production of carbon oxides. On the other hand, high activity and selectivity is also observed over catalysts rich in cerium ( with Ni/ Ce ratios between 0.2 and 3). In this case, a different mechanism can be proposed in which the high capacity of CeO2 to bomb oxygen from bulk to surface and the partial formation of NiO and Ce1-xNixO2 facilitates a faster reoxidation of active Ni-sites by a synergic effect improving catalytic activity. (C) 2011 Elsevier B.V. All rights reserved.