Preparation, characterization and application of the magadiite based mesoporous composite material of catalytic interest

The synthesis of a new type of mesoporous materials by intercalation of silica between magadiite layers was carried out. For the preparation of the composite material, reactive silica gels with compositions characteristic for the synthesis of MCM-41 were used. Samples synthesized with various compositions were characterized by X-ray diffraction, IR and NMR spectroscopy, thermal analysis, BET measurements as well as scanning and transmission electron microscopy. These techniques showed that the composite samples are ordered materials with a pore opening around 4 nm, a specific surface area over 700 m(2) g-l, a regular pillared structure and tetrahedrally coordinated aluminum in the silica walls. The acidity of the samples, determined by the adsorption of pyridine and monitored by IR spectroscopy, was negligible for pure silica composites, while significant Br phi nsted and Lewis acid sites in different concentrations were found for the aluminum-containing materials. The catalytic activity of the samples followed the same trend in acid-catalyzed double bond isomerization of I-butene to 2-butenes and in the alkylation of toluene with benzyl chloride. Physisorption of benzene and chemisorption of methanol were concluded from in situ adsorption measurements by IR spectroscopy. The thermal and mechanical stabilities of the composite materials were higher than those of the MCM-41, irrespective of the composition. (C) 2000 Elsevier Science B.V. All rights reserved.