Amount and nature of sulfates at the surface of sulfate-doped zirconia catalysts

Two families of sulfate-doped zirconia catalysts (sd-ZrO2) have been investigated by dosing the surface sulfates, and characterizing the solids by X-ray diffraction (XRD), high-resolution transmission electron microscopy (HRTEM) and Fourier-transform infrared (FTIR) spectroscopy. The most suitable analysis method is discussed. The spectral features of surface sulfates, responsible for the superacid catalytic properties of sd-ZrO2, have been related to preparative parameters such as the sulfation procedure, the sulfate content, the crystal phase of the support, the thermal treatment of the solid after sulfation and the vacuum activation temperature of the catalyst.