STEIN RESEARCH GROUP

POROUS SOLIDS — NANOCOMPOSITES — SELF-ASSEMBLED FRAMEWORKS

Surface Modification of Mesoporous Sieves with Inorganic Group

Modification of the internal pore surfaces with metal oxide surface groups is possible in mesoporous silicates. Titanium dioxide was grafted onto the pore surface of MCM-41 by reacting TiCl₄ in hexanes with the surfactant-filled (as-synthesized) silicate support. The titania formed well-dispersed isolated titania nanoclusters within the channel structures. The surfactant present in the pores was necessary to prevent the creation of larger TiO₂ agglomerates which would block the channels. The titania-grafted MCM-41 samples exhibited good catalytic activity for photobleaching of rhodamine-6G and for oxidation of alpha-terpineol; however, product selectivity was low. Zinc- and magnesium-manganese oxide particles were also grown in the pores of MCM-41 using a procedure adapted from a mild synthesis for layered manganese oxides. In addition, we investigated methods of incorporating polyoxometalate clusters in mesoporous or macroporous silica structures to take advantage of the properties of both the polyoxometalate and the silica support. These materials were evaluated as oxidation catalyts.

         
       Fig. 1. Transmission electron micrograph of MCM-41