Carbon dioxide in the dehydrogenation of isobutane over VMgOx

On the basis of catalytic tests and kinetic investigations, the role of carbon dioxide in the conversion of isobutane to isobutene over VMgOx catalyst was studied. It was shown that both the high temperature (>826 K) and the presence of VMgOx catalyst are required for activation of CO2 molecule. Presented results stay in agreement with thermodynamic analysis of the isobutane dehydrogenation process, where the two-step dehydrogenation pathway (i.e., simple dehydrogenation followed by reverse water gas shift reaction) was the most favorable way of isobutene synthesis. Moreover, insufficient oxidizing property of carbon dioxide allows to exclude possibility of the redox-cycle mechanism over VMgOx catalyst. (C) 2009 Elsevier B.V. All rights reserved.