Heterogeneous catalysis is central to chemical and polymer manufacturing, a variety of environmental remediation processes, and many other chemo-centric endeavors. Appropriately chosen supports can be used to modulate the electronic properties of deposited active species, potentially yielding desirable changes in catalytic activity and/or chemical selectivity. NU-1000, an eight-connected MOF, consisting of Zr6(μ3–O)4(μ3–OH)4(H2O)4(OH)48+ nodes and tetratopic 1,3,6,8-(p-benzoate)pyrene (TBAPy4−) linkers, has proven effective as a support for well-defined oxy-metal catalysts. In our previous work, Ni-AIM-NU-1000 has been shown to be an effective catalyst for ethylene hydrogenation and also for ethylene oligomerization. It is well-documented for molecular catalysts that changing the chemical environment proximal to a catalytically active site can greatly affect site’s catalytic performance. Here, we report ALD/SALI-based functionalization of MOF nodes can offer a general way of defining the environment around a subsequently installed NixOy catalytic cluster. Hexafluoroacetylacetonate (Facac−) and acetylacetonate (Acac−) units have been introduced as nonstructural ligands, which altered the selectivity of the oxy-Ni(II) cluster, shifting it from broad ethylene oligomerization to exclusively dimerization, i.e. butene formation. What’s more, changing the functional group on the coordinated ligands systematically tune the electronic environment surrounding the Zr6 nodes to the subsequently installed oxy-Ni(II) clusters and manifested in systematic variation of catalytic activity for ethylene hydrogenation. The materials design, synthesis, characterization and catalysis performance will be discussed in details.

Introducing nonstructural ligands to MOF nodes to tune the activity and selectivity of node-supported nickel catalysts for ethylene conversion

2019 Spring National Meeting

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