TEXTURAL CHARACTERIZATION OF SILICA AND SILICA-ALUMINA GELS - COMPARISON OF DIFFERENT TECHNIQUES

The porous texture of silica and silica-alumina hydrogels has been stu died by means of thermoporometry measurements. The texture of the xero gels resulting from spray-drying of silica-alumina hydrogels is then e valuated by different methods: BET, Hg-porosimetry and thermoporometry . As each method is based on different physical principles and assumpt ions, differences are observed between the results. However, these res ults are complementary and their comparison leads to a better knowledg e of the texture of the catalyst particles. A good agreement is observ ed between thermoporometry and nitrogen adsorption-desorption measurem ents, whereas mercury porosimetry results are very different. Silica-a lumina gels appear as mainly mesoporous materials.