Alumina-promoted sulfated zirconia system: Structure and microstructure characterization

The Al2O3 promotion of ZrO2/SO4 has been shown to influence n-butane isomer ization activity. In this paper we report a study of the influence of a sma ll addition of Al2O3 (0.6-10.3 wt %) onto the ZrO2 structure and microstruc ture. The addition of alumina is related to an increase of the surface area . A detailed X-ray diffraction analysis by the use of the modified Rietveld method allowed us to follow the changes in the crystalline phases and to q uantify the amount of amorphous phase. When the Al2O3 content is increased, a decrease of the ZrO2 particle sizes is observed, paralleled by an increa se of the amorphous phase. When the Al2O3 content is larger than 3.7 wt %, only amorphous phase can be detected. No crystalline peaks of Al2O3 were ev er observed. These data were supported also by TEM and Raman measurements.