Ultrathin
nickel-based metal–organic framework nanosheets
(Ni-UMOFNs) were formed from NiCl2·6H2O
and benzene-1,4-dicarboxylate through a sonication exfoliation method.
In Ni-UMOFNs, the Ni atoms are octahedrally coordinated by six O atoms
to form pseudo-octahedra which are further edge/corner connected with
each other to form 2D layers separated by benzene-1,4-dicarboxylate
linkers. On the Ni-UMOFN surfaces, Ni centers are partially five coordinated
owing to the termination of benzene-1,4-dicarboxylate ligands, and
these coordinated unsaturated metal sites can be used as catalytic
active sites. In this work, Ni-UMOFNs were utilized as ethylene dimerization
catalysts in the presence of an alkylaluminum cocatalyst for the first
time. The Ni-UMOFN catalytic system showed moderate catalytic activity
but high selectivity to 1-butene up to 92.8% under optimal conditions.
The optimal Ni-UMOFN catalyst can be reused at least four times without
considerable loss in the catalytic activity and selectivity to 1-butene.
Extraordinarily, the outstanding level of reusable property is due
to continuous exposure of fresh unsaturated metal active sites when
the original metal centers on the catalyst surface are used and exfoliated,
just like a snake’s molting.
A new metal–organic framework {[Zn2(Htzba)2(dmtrz)]·(CH3)2NH}n (1) has already been solvothermally synthesized that exhibits a high CO2 uptake capacity.
MIL-100 and MIL-101 were synthesized and evacuated to generate a series of heterogeneous catalysts for isomerization of 1-butene. Their crystal structures and pore properties were characterized by PXRD and nitrogen adsorption−desorption techniques. These catalysts showed high catalytic activity for isomerization of 1-butene and high selectivities for 2-butene at room temperature. Moreover, the MIL-101 (Cr) catalyst evacuated at 200 °C exhibited the largest BET surface area of 2759 m 2 g −1 . At the same time, conversion of 1-butene and the highest selectivity to 2-butene were up to 93.38% and 98.08%, respectively. This work indicated that MOFs containing coordinatively unsaturated metal sites might be promising catalysts for olefin isomerization under mild conditions.
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