1-Hexanol Oxidation over Magnesia-Supported Vanadium and Barium Oxide Catalysts

Magnesia-supported vanadium oxide (VMgO) catalysts with different vanadium loadings, viz. 5, 10, 15, and 20%, were prepared by the wet impregnation method. Due to its good catalytic performance during 1-hexanol oxidation in this study, the 15-VMgO catalyst was doped with different amounts of barium. The prepared catalysts were characterized by inductively coupled plasma optical emission spectroscopy (ICP-OES), infrared spectroscopy, ultraviolet–visible spectroscopy (UV–Vis), and powder X-ray diffraction (XRD). The prepared VMgO and barium-doped (BaVMgO) catalysts were tested for the oxidation of 1-hexanol in the liquid phase using hydrogen peroxide as an oxidant and acetonitrile as a solvent. Within the range of the vanadium loadings studied, the 15-VMgO catalyst showed the highest catalytic activity and hexanal selectivity. Adding barium as a dopant to the 15-VMgO catalyst improved 1-hexanol conversion, with the 2-BaVMgO catalyst showing the best catalytic performance (1-hexanol conversion and hexanal selectivity of 35 and 98%, respectively). Different 1-hexanol to H2O2 molar ratios were studied over the 2-BaVMgO catalyst, and hexanal selectivity was found to be very sensitive to the changes in the molar ratio; the molar ratio of 1.0 was found to be the optimal one. The results indicated that the good catalytic performance was probably related to the synergistic coexistence of pyro- and orthovanadate phases. Moreover, the catalyst was stable for about 5 hours on stream.