Improvement of structural integrity of mesoporous molecular sieves for practical applications

Abstract

The synthesis and post-synthetic metal grafting of mesoporous silica molecular sieves designated as MCM-41 (P6m hexagonal), MCM-48 (Ia3d cubic), KIT-1 (disordered network), SBA-1 (Pm3n cubic) and MSU-1 (disordered sponge) has been studied in order to improve the integrity of the mesoporous structures. Our results show that disordered materials are obtained in the form of irregular particles with uniform pore size distribution. On the other hand, the ordered materials can be synthesised in the form of single crystallites with excellent structural integrity. The hydrothermal stability of the materials can be improved by the addition of salts during synthesis. The mesoporous silica can be converted to the corresponding metallosilicate analogues by grafting metal elements onto the silica frameworks using non-aqueous solutions of aluminium chloride, zinc acetate, copper acetate and iron acetate. The resultant metallosilicates, which maintain the high structural integrity of the pure silica forms, are suitable for applications in catalysis, ion exchange and adsorption.