Vanadium-Node-Functionalized UiO-66: A Thermally Stable MOF-Supported Catalyst for the Gas-Phase Oxidative Dehydrogenation of Cyclohexene

Abstract

The OH groups on the Zr-based nodes of ultrastable UiO-66 can be metallated with V V ions in a facile fashion to give the derivative VUiO-66. This metallated MOF exhibits high stability over a broad temperature range and displays high selectivity for benzene under low-conversion conditions in the vapor-phase oxidative dehydrogenation of cyclohexene (activation energy ∼110 kJ/mol). The integrity of the MOF is maintained after catalysis as determined by PXRD, ICP-AES, and SEM.

Size effect of the active sites in UiO-66-supported nickel catalysts synthesized via atomic layer deposition for ethylene hydrogenation

“…19 This assertion is in line with diffuse reflectance Fourier transform infrared spectra (DRIFTS) for the MOF before and after single-AIM-cycle nickel incorporation. Relative to the “before” spectrum, the “after” spectrum shows a modest decrease in intensity of a peak at 3674 cm −1 , which is known to be due to O-H stretches associated with node water and terminal-hydroxide ligands; 47 see Figure S3.…”

“…15 The decoration can be accomplished via A LD i n M OFs (AIM) 16–18 or s olvothermal deposition i n M OFs (SIM) 19–22 —as well as by AIM and SIM in combination. 23 Depending, of course, on their specific chemical composition, the resulting MOF-supported clusters or single metal ions can be rendered competent for photocatalytic H 2 generation, 24 electrocatalytic O 2 production, 25 solution-phase alkene epoxidation, 26, 27 and gas-phase ethylene hydrogenation and oligomerization, 13, 21, 28 hexene polymerization, 20 and propane oxidative dehydrogenation, 29 among other reactions.…”

“…38, 39 It was also chosen because of the comparative enhanced variability with which single-metal-atom active sites can be introduced. 19, 21, 40, 41 Briefly, the nodes of UiO-66 are ideally twelve-connected to carboxylate-terminated linkers, leaving no sites for the nodes to present ALD-reactive aqua or terminal hydroxo ligands. (In contrast, mesoporous Zr-MOFs such as PCN-222 (MOF-545), 42, 43 NU-1000, 16 NU-1200, 44 and MOF-808 45 are six- or eight-connected, with the unused linker-connection sites instead being occupied by ligated water or hydroxide, i.e.…”

Targeted Single-Site MOF Node Modification: Trivalent Metal Loading via Atomic Layer Deposition

“…3−6 Although the vast majority of MOF catalysis work focuses on linkers as catalysts 7 for condensed-phase reactions, a few reports of node-based catalysis have also appeared, 8−16 including at least one for high temperature (350°C) heterogeneous catalysis of a gas-phase oxidation reaction. 17 Increasingly popular as nodes for these types of studies are hexa-zirconium(IV)oxo/hydroxo/aqua species and their hafnium(IV) analogues. The lability and reactivity of the nodes' oxygen-rich ligandsspecifically, aqua and terminal hydroxo ligandsallows for site-specific functionalization, both with nonstructural organic ligands 18−22 and, in principle, with nonstructural metal ions.…”

Immobilization of Cu Complex into Zr-Based MOF with Bipyridine Units for Heterogeneous Selective Oxidation

“…The controllable nanospace in the framework of MOFs is a suitable candidate for a host of catalytically active species and will provide an accurately controlled reaction field. [30][31][32][33] In this context, it is anticipated that immobilization of Cu homogeneous complexes into MOF structures will enable the development of efficient and recyclable heterogeneous catalysts. We herein report the immobilization of CuBr2 within Zr-based MOF with an organic linker of 2,2'-bipyridine-5,5'-dicarboxylic acid (Zr-MOF-bpy-CuBr2) and its application for selective oxidation of cyclooctene to cyclooctene oxide, as shown in Fig.…”