A combined study by XPS, Raman, diffuse reflectance spectroscopy and analytical electron microscopy of the influence of the sequence of impregnation on the state and dispersion of cobalt in CoMo/Al 2 O 3 catalysts

Abstract XPS, Raman, diffuse reflectance spectroscopy and analytical electron microscopy techniques were used to investigate the influence of the sequence of impregnation (Mo or Co first) on the state and dispersion of cobalt in CoMo/Al 2 O 3 catalyst in its precursory oxidic state (3 wt% Co 3 O 4 and 12 wt% MoO 3 ). The results indicate that impregnating Mo first promotes both the dispersion of the cobalt containing phase and the formation of CoAl 2 O 4 like species at the expense of ‘free’ cobalt in Co 3 O 4 like compounds.