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 assynthesized 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 Si-29 NMR spectroscopy, nitrogen adsorption and scanning electron microscopy. (C) 2000 Elsevier Science B.V. All rights reserved.