Characteristics of Ti-MCM-41 Post-synthesized in Organic or Aqueous Solution using Organo-titanium Compounds as Ti Sources

Abstract

Post-synthetic procedure has been proposed using organo-titanium compounds as Ti source in toluene or aqueous solution to prepare Ti-MCM-41. Ti-MCM-Tn, prepared using Ti-source dissolved in toluene solution, exhibited well-defined 2d-hexagonal structure, and octahedrally coordinated Ti (VI) was mainly introduced as extra-framework species. Ti-MCM-Wn, prepared from Ti-source in aqueous solution, gave high surface area and partially deteriorated 2d-hexagonal structure. Tetrahedrally coordinated Ti (IV) species was selectively incorporated into the framework of the Ti-MCM-Wn samples. Catalytic activity for oxidation reactions of cyclohexene and selectivity to the formation of cyclohexene oxide were correlated with the concentration of Ti (IV) species and the fraction of Ti (IV) in titanium species located at the surfaces of the pores in the Ti-MCM catalysts, respectively.