Effect of supports on the structure and activity of vanadium-chromium oxide catalysts for ammoxidation of 3-picoline

Bulk and Nb2O5-, MgF2-, TiO2-, and SiO2-supported vanadium-chromium oxide catalysts were prepared by the incipient wetness impregnation method and investigated for the ammoxidation of 3-picoline to nicotinonitrile at 310–400 °C. The physical and chemical properties of the catalysts were assessed by X-ray diffraction, N2 adsorption-desorption, H2-temperature-programmed reduction, and NH3-temperature-programmed desorption. The surface area of the supports influenced the formation of the active components of the catalysts: high surface area encouraged the formation of monoclinic CrVO4 whereas low surface area favored the formation of orthorhombic CrVO4. The high reducibility of vanadium in the catalyst and the large number of surface active sites resulted in higher 3-picoline conversion efficiencies. The high selectivity was attributed to the low surface acidity of the catalysts. Reaction temperature showed a positive effect on the catalytic performance for it could increase 3-picoline conversion and maintain nicotinonitrile selectivity.

Graphical AbstractHighly efficient vanadium-chromium oxide catalysts for ammoxidation of 3-picoline have been prepared. The acidity and reducibility had great influence on the catalytic activity and selectivity.Figure optionsDownload full-size imageDownload as PowerPoint slide