Temperature-programmed desorption vs. N₂ desorption in determining pore-size distribution of mesoporous silica molecular sieves

Two mesoporous silica molecular sieves, one synthesized by cationic template method and another by neutral template route, were characterized for their pore-size distribution by a novel Temperature-Programmed Desorption (TPD) method and the widely used N₂ desorption method. The pore-size distributions determined by the two methods agree quite well and are within experimental errors. For example, TPD method gave a pore-size distribution (radius) centered at 14 Å while N₂ desorption method showed a peak centered at 13.3 Å. for the mesoporous silica prepared by cationic template route. The new TPD method based on thermogravimetric analysis is a viable option for mesopore characterization of silica-based materials.