Spectroscopic characterization of [formula omitted] and [formula omitted] catalysts

Abstract

X-ray photoelectron spectroscopy (ESCA or XPS), laser Raman spectroscopy (LRS), and X-ray diffraction (XRD) have been used to characterize the dispersion and chemical state of a series of TiO 2 Al 2 O 3 carriers and a series of 3% Co Al 2 O 3 TiO 2 catalysts. It was found that titania is well dispersed on alumina for Ti loadings less than 14 wt%. The formation of a TiO 2: Al 2O 3 surface phase occurred for carriers in the 1 to 6 wt% Ti range. Formation of anatase occurred, in addition to the TiO 2:Al 2O 3 surface phase, at loadings in excess of 6 wt% Ti, with the amount of anatase increasing with increasing titania loading. ESCA data indicate that the dispersion of cobalt supported on the titania-modified alumina carriers increased with increasing titania loading. XRD and LRS results show that the increase in dispersion can, in part, be ascribed to the formation of a surface cobalt phase at the detriment of the Co 3O 4 phase.