STRUCTURAL AND TEXTURAL PROPERTIES OF MCM-41 MESOPOROUS MOLECULAR SIEVES CONTAINING NB, V, MO -ALTERNATIVE CATALYSTS FOR HYDROCARBONS OXIDATION

摘要

In 1992 the synthesis of a new family of mesoporous molecular sieves designated as M41S was reported [1]. MCM-41, one member of this family, exhibits uniform cylindrical pores in hexagonal arrangement and is produced using rod-like micelles of cationic surfactant molecules as a template. Mesoporous molecular sieves of MCM-41 type opened an opportunity for the design of catalytically active sites inside the uniform channels with controllable nano-order pore diameter. However, a pure silicate MCM-41 showed limited catalytic applications [2] and therefore, incorporation of metal centers in the silicate framework is necessary for their use in the catalysis. Isomorphous substitution of silicon with a transition metal is an excellent strategy in creating catalytically active sites for reactive molecules in the design of new heterogeneous catalysts. It is possible to obtain highly dispersed and isolated active sites in the silicate framework. Coordination and stabilization of the transition metal ion by the ordered matrix can significantly affect its catalytic behavior and lead to catalysts with new and often improved properties.