Effects of boron and barium dopants on VMgO catalysts employed in the oxidative dehydrogenation of n-octane

Boron and barium were employed as dopants for the VMgO system. The catalysts were characterized by ICP-OES, BET, IR, powder XRD, EDX, TPR-H2, TPD-NH3, XPS, and 51V MAS NMR. These catalysts were used for the oxidative dehydrogenation of n-octane in a continuous flow fixed bed reactor using air as an oxidant. Catalytic tests were carried out at a GHSV of 8000 h−1 and an n-octane to oxygen ratio of 0.8. The dopants induced some changes in the catalysts' properties, e.g. the acid-base character, the reducibility, and the symmetry and the heterogeneity of the VO4 tetrahedra. Changes in the catalytic performance were also observed. Doping with barium enhanced styrene selectivity and yield, while boron adversely affected the activity and the ODH selectivity of the VMgO system. The catalytic activities may be explained by the reducibility of the vanadium species.