Isomorphic Substitution and Postsynthesis Incorporation of Zirconium into MCM-48 Mesoporous Silica

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