Textural characterization of silica and silica-alumina gels: Comparison of different techniques

The porous texture of silica and silica-alumina hydrogels has been studied by means of thermoporometry measurements. The texture of the xerogels resulting from spray-drying of silica-alumina hydrogels is then evaluated by different methods: BET, Hg-porosimetry and thermoporometry. As each method is based on different physical principles and assumptions, differences are observed between the results. However, these results are complementary and their comparison leads to a better knowledge of the texture of the catalyst particles. A good agreement is observed between thermoporometry and nitrogen adsorption-desorption measurements, whereas mercury porosimetry results are very different. Silica-alumina gels appear as mainly mesoporous materials.