Chemistry

Making Butene in MOFs

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Science  29 Mar 2013:
Vol. 339, Issue 6127, pp. 1497
DOI: 10.1126/science.339.6127.1497-a

Although homogeneous organometallic catalysts can be very efficient in solution, it can be advantageous for separations and catalyst recovery to “heterogenize” them by using linkers to attach them to a support. However, typical high–surface-area metal oxide materials used as supports for conventional heterogeneous catalysts can deactivate organometallic catalysts through unwanted interactions with the support or between nearby catalyst molecules. One alternative has been to incorporate catalysts into high–surface-area metal organic framework (MOF) materials, and Canivet et al. used this method with an olefin oligomerization catalyst. They started with (Fe)MIL-101-NH2, in which trimeric iron(III) octahedral clusters are linked by 2-aminoterephthalate ligands. This MOF has the high pore volume needed to accommodate a nickel(II) catalyst as well as reactants and products. They achieved different densities of N,N-chelating centers for nickel in the MOF through reaction with 2-pyridine carboxaldehyde, which formed a methanimino bridge between some of the 2-aminoterephthalate linkers and pyridyl groups. These materials were then suspended in heptane and exposed to ∼15 atm of ethylene in the presence of diethylaluminum chloride. One of them, which had a loading of 10 nickel centers per MOF cage, exhibited >95% selectivity for forming 1-butene.

J. Am. Chem. Soc. 135, 4195 (2013).

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