title: Stable Metal-Organic Framework-Supported Niobium Catalysts.
abstract: Developing structurally well-defined, supported oxide catalysts remains a significant challenge. Here, we report the grafting of Nb(V) oxide sites onto the nodes of the Zr-based metal organic framework (MOF) NU-1000 as a stable, well-defined catalyst support. Nb(V) oxide was deposited with loadings up to 1.6 mmol/g via two postsynthetic methods: atomic layer deposition in a MOF, and solution-phase grafting in a MOF. Difference envelope density measurements indicated that the two synthetic methods resulted in different local structures of the Nb(V) ions within NU-1000. Despite their high Nb(V) loadings, which were equivalent to >60% surface coverage, nearly all Nb(V) sites of the MOF-supported catalysts were active sites for alkene epoxidation, as confirmed by phenylphosphonic acid titration. The MOF-supported catalysts were more selective than the control Nb-ZrO2catalyst for cyclohexene epoxidation with aqueous H2O2and were far more active on a gravimetric basis.
authors: Sol
authors: S
authors: Ahn
authors: Nicholas E
authors: NE
authors: Thornburg
authors: Zhanyong
authors: Z
authors: Li
authors: Timothy C
authors: TC
authors: Wang
authors: X-ray Science Division, Advanced Photon Source, Argonne National Laboratory , 9700 South Cass Avenue, Argonne, Illinois 60439, United States.
authors: Leighanne C
authors: LC
authors: Gallington
authors: X-ray Science Division, Advanced Photon Source, Argonne National Laboratory , 9700 South Cass Avenue, Argonne, Illinois 60439, United States.
authors: Karena W
authors: KW
authors: Chapman
authors: Justin M
authors: JM
authors: Notestein
authors: Joseph T
authors: JT
authors: Hupp
authors: Department of Chemistry, Faculty of Science, King Abdulaziz University , Jeddah 21589, Saudi Arabia.
authors: Omar K
authors: OK
authors: Farha