Isomorphic substitution and postsynthesis incorporation of zirconium into MCM-48 mesoporous silica

We describe the introduction of zirconium metal centers into the cubic phas e of mesoporous silica. Two methods of zirconium incorporation were compare d consisting of hydrothermal Si/Zr coprecipitation and postsynthesis functi onalization of surface silanols with zirconium propoxide. Nitrogen sorption and X-ray powder diffraction confirmed that both the structure, high surfa ce area, and narrow pore size distribution were maintained. FTIR, UV/Vis, a nd EXAFS were then employed to characterize the local metal atom bonding an d coordination environment. Grafting with zirconium propoxide was found to produce the most isolated metal species.