Stabilized MCM-48/VOx catalysts:: synthesis, characterization and catalytic activity

The high synthesis cost, the poor hydrothermal stability of the pore structure and the extensive leaching of the active metal sites in liquid phase heterogeneous catalysis are three of the most important drawbacks for the industrial use of the newly developed mesoporous crystalline materials (MCM-41, MCM-48, HMS, FSM, ...). In this study, we present an integrated approach that tackles these three problems simultaneously. High quality MCM-48 is prepared by a method of surfactant extraction and recuperation. The surface of the material is stabilized using a bifunctional silane, rendering the surface essentially hydrophobic, but leaving sufficient secondary anchoring sites for a further activation with VO(acac)(2) and final calcination. The final catalyst is thoroughly characterized and its catalytic and mechanical behavior is evaluated. It is shown that these materials can withstand severe hydrothermal conditions and that the leaching of the catalytic active species in liquid media is very strongly reduced. The obtained catalysts are active and selective and can be regenerated without significant loss of activity. (C) 2001 Elsevier Science B.V. All rights reserved.