PREPARATION AND CHARACTERIZATION OF HIGH-SURFACE-AREA ALUMINA-TITANIASOLID ACIDS

As part of a systematic study of solid acids, a series of high surface area single-phase alumina-titania mixed oxides were prepared. These m aterials were found to have higher surface areas, greater porosity and enhanced specific surface acidity than comparable alumina-titania sol id acids reported in the literature. The thermal stability of the phas es and their textural and physicochemical properties have been studied over a range of Al/Ti compositions and for calcinations up to 1000 de grees C. The samples were characterized by differential thermal analys is-thermogravimetry, X-ray diffraction, nitrogen physisorption and X-r ay photoelectron spectroscopy. Surface acidity was measured by tempera ture programmed desorption and in situ Fourier transform-infrared spec troscopy, using ammonia as a probe molecule. The strength and density of the acid sites were proportional to the Ti-content.