Physicochemical features of the formation of siliceous porous mesophases. 4. Effect of duration and temperature of the hydrothermal treatment on the structural and textural properties

The results of investigation of mesoporous mesophase materials C12--SiO₂--MMM and C16--SiO₂--MMM prepared at the optimized composition of the reaction mixture and different durations of hydrothermal treatment (HTT) at 120 °C and 140 °C are presented. Hydrothermal treatment at 120 °C influences slightly the specific surface area and the volume of the mesopores but gives a more ordered structure. Prolonged HTT at 140 °C results in irreversible structure degradation. The samples obtained with the optimal HTT duration are characterized by the minimum width of X-ray reflections, the maximum surface and volume of mesopores, and the minimum external surface.