Hydrothermal stability of MCM-48 improved by post-synthesis restructuring in salt solution

The hydrothermal stability of the mesoporous silica molecular sieves MCM-48 has been found to increase if the as-synthesized materials containing surfactant are heated in an aqueous solution of salts. Although the optimum treatment conditions depended on details of the synthesis procedures, this post-synthesis technique led to a significant improvement in the hydrothermal stability of various MCM-48 materials that were synthesized using cationic surfactants alone or cationic-neutral surfactant mixtures. These results were concluded as due to the restructuring effects of the pore walls by magic angle spinning ²⁹Si NMR spectroscopy, nitrogen adsorption and scanning electron microscopy.