MCM-41 anchored manganese salen complexes as catalysts for limonene oxidation

This work reports the covalent attachment of three different salen-based complexes on MCM-41, using two different methods. In both methods, a diisocyanate is used as a binder. All the prepared catalysts were tested on the liquid phase limonene oxidation reaction, using diluted t-butyl hydroperoxide as oxidant. Limonene oxide, carveol, carvone and a polymer were the main products obtained. The preservation of the MCM-41 channel system was checked by X-ray diffraction, nitrogen adsorption analysis and transmission electron microscopy (TEM). Catalytic activity seems to increase in the following order: Mn(4-OHsalen) < Mn(4-OHsalhd) < Mn(4-OHsalophen). The most active catalysts were used in four consecutive experiments without any activity loss, confirming the success of the anchoring process and the catalysts stability. (C) 2009 Elsevier Inc. All rights reserved.