Oxidative dehydrogenaiton of propane over V_2O_5/TiO_/SiO_2 catalysts obtained by grafting titanium and vanadium alkoxides on silica

摘要

Oxidative dehydrogenation of propane on V_2O_5/TiO_2/SiO_2 catalysts, prepared by grafting, was investigated in the temperature range 673-773 K. The prepared samples were characterised by X-ray diffraction (XRD), Fourier-transform infrared spectroscopy (FTIR), UV-VIS diffuse reflectance (DRUV-VIS),temperature programmed reduction (TPR) and O_2 chemisorption. Crystalline V_2O_5 was not revealed on any sample, although the dispersion of the surface species steeply decreased with increasing vanadium loading. Non-isolated tetrahedral V~(5+) were present on the surface at any vanadium concentration. In the case of A(5) catalyst, the presence of octahedral vanadium species was also observed.