title: An Exceptionally Stable Metal-Organic Framework Supported Molybdenum(VI) Oxide Catalyst for Cyclohexene Epoxidation.
abstract: Molybdenum(VI) oxide was deposited on the Zr6node of the mesoporous metal-organic framework NU-1000 via condensed-phase deposition where the MOF is simply submerged in the precursor solution, a process named solvothermal deposition in MOFs (SIM). Exposure to oxygen leads to a monodisperse, porous heterogeneous catalyst, named Mo-SIM, and its structure on the node was elucidated both computationally and spectroscopically. The catalytic activity of Mo-SIM was tested for the epoxidation of cyclohexene. Near-quantitative yields of cyclohexene oxide and the ring-opened 1,2-cyclohexanediol were observed, indicating activity significantly higher than that of molybdenum(VI) oxide powder and comparable to that of a zirconia-supported analogue (Mo-ZrO2) prepared in a similar fashion. Despite the well-known leaching problem of supported molybdenum catalysts (i.e., loss of Mo species thus causes deactivation), Mo-SIM demonstrated no loss in the metal loading before and after catalysis, and no molybdenum was detected in the reaction mixture. In contrast, Mo-ZrO2led to significant leaching and close to 80 wt % loss of the active species. The stability of Mo-SIM was further confirmed computationally, with density functional theory calculations indicating that the dissociation of the molybdenum(VI) species from the node of NU-1000 is endergonic, corroborating the experimental data for the Mo-SIM material.
authors: Department of Chemistry and Chemical and Biological Engineering, Northwestern University , 2145 Sheridan Road, Evanston, Illinois 60208, United States.
authors: Hyunho
authors: H
authors: Noh
authors: Department of Chemistry and Chemical and Biological Engineering, Northwestern University , 2145 Sheridan Road, Evanston, Illinois 60208, United States.
authors: Yuexing
authors: Y
authors: Cui
authors: Department of Chemistry and Chemical and Biological Engineering, Northwestern University , 2145 Sheridan Road, Evanston, Illinois 60208, United States.
authors: Aaron W
authors: AW
authors: Peters
authors: Department of Chemistry, Supercomputing Institute, and Chemical Theory Center, University of Minnesota , Minneapolis, Minnesota 55455, United States.
authors: Dale R
authors: DR
authors: Pahls
authors: Department of Chemistry, Supercomputing Institute, and Chemical Theory Center, University of Minnesota , Minneapolis, Minnesota 55455, United States.
authors: Manuel A
authors: MA
authors: Ortuño
authors: Department of Chemistry and Chemical and Biological Engineering, Northwestern University , 2145 Sheridan Road, Evanston, Illinois 60208, United States.
authors: Nicolaas A
authors: NA
authors: Vermeulen
authors: Department of Chemistry, Supercomputing Institute, and Chemical Theory Center, University of Minnesota , Minneapolis, Minnesota 55455, United States.
authors: Christopher J
authors: CJ
authors: Cramer
authors: Department of Chemistry, Supercomputing Institute, and Chemical Theory Center, University of Minnesota , Minneapolis, Minnesota 55455, United States.
authors: Laura
authors: L
authors: Gagliardi
authors: Department of Chemistry and Chemical and Biological Engineering, Northwestern University , 2145 Sheridan Road, Evanston, Illinois 60208, United States.
authors: Joseph T
authors: JT
authors: Hupp
authors: Department of Chemistry and Chemical and Biological Engineering, Northwestern University , 2145 Sheridan Road, Evanston, Illinois 60208, United States.|Department of Chemistry, Faculty of Science, King Abdulaziz University , Jeddah 21589, Saudi Arabia.
authors: Omar K
authors: OK
authors: Farha