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

The high synthesis cost, the poor hydrothermal stability of the pore struct ure and the extensive leaching of the active metal sites in liquid phase he terogeneous catalysis are three of the most important drawbacks for the ind ustrial 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 pr epared by a method of surfactant extraction and recuperation. The surface o f the material is stabilized using a bifunctional silane, rendering the sur face essentially hydrophobic, but leaving sufficient secondary anchoring si tes for a further activation with VO(acac)(2) and final calcination. The fi nal catalyst is thoroughly characterized and its catalytic and mechanical b ehavior is evaluated. It is shown that these materials can withstand severe hydrothermal conditions and that the leaching of the catalytic active spec ies in liquid media is very strongly reduced. The obtained catalysts are ac tive and selective and can be regenerated without significant loss of activ ity. (C) 2001 Elsevier Science B.V. All rights reserved.