A vanadium-magnesium oxide catalyst (VMgO) with a V 2 O 5 concentration of 15% by weight was employed for the oxidative dehydrogenation of n-octane to produce the corresponding linear octenes and C8 aromatics. The catalyst was synthesized by the wet impregnation method, and was characterized by in situ XRD, TGA-DSC, and 51 V MAS NMR. The used catalysts were characterized by powder XRD, BET, pore volume analysis, SEM, EDX, ICP-OES, and 15 V MAS NMR. The catalytic testing was carried out at different n-octane/O 2 molar ratios (viz. 0.1, 0.4, 0.8, 1.2, and 1.6) at a GHSV of 8,000 h -1 in a continuous flow fixed bed reactor. The results showed that the catalytic performance with regard to both activity and selectivity was very sensitive to the strength of the oxidative environment (n-octane to oxygen ratio). No phasic changes were observed in the used catalysts. However, some textural changes were induced by the catalytic testing.

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Magnesium oxide was prepared and used as a catalyst for the dehydrogenation of n-octane. The catalyst was characterized by ICP-OES, BET, powder XRD, IR, H 2 -TPR and SEM. The catalyst was tested for the oxidative dehydrogenation of n-octane using a continuous flow fixed bed reactor at a GHSV of 6000 h À1 and n-octane/oxygen (O 2 ) molar ratio of 0.8. Octenes were found to be the dominant dehydrogenation products, with 2-octenes being the dominant isomers. Among the C8 aromatics, ethylbenzene was the most-formed product, followed by styrene and o-xylene. The aromatization of n-octane was predominantly through the C1-C6 mode of cyclization. ª 2014 The Authors. Production and hosting by Elsevier B.V. on behalf of King Saud University. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/3.0/).

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Boron-and barium-doped vanadium-magnesium oxide catalysts (BVMgO and BaVMgO) were synthesized by the wet impregnation method and were used for the oxidative dehydrogenation of n-octane at different noctane/O 2 molar ratios. The catalysts were characterized by ICP-OES, in situ XRD, 51 V MAS NMR, SEM, EDX and TGA-DSC. The catalytic tests were carried out in a continuous flow fixed bed reactor. The incorporation of boron and barium as dopants into the VMgO system resulted in catalysts with some differences in properties, such as the details of phase transformations, porosity and degree of hydration. The catalytic performance was affected by the strength of the oxidative environment. Moreover, incorporation of barium enhanced the catalytic performance of VMgO, while the addition of boron adversely affected the performance of VMgO over all n-octane/O 2 molar ratios with regard to both activity and oxidative dehydrogenation selectivity.

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