(561a) Metal-Organic Frameworks Encapsulated Metal Nanoparticles for Heterogeneous Catalysis

Metal–organic frameworks (MOFs) are a new class of porous materials, which have potential applications in a wide range of areas including catalysis, gas storage, separation, and energies. Owing to their high surface area, porosity, and chemical tunability, the utilizations of MOFs in heterogeneous catalysis have recently attracted tremendous attention.

We employed stable MOFs as support for highly dispersed metal nanoparticles, such as Au, Pt, Pd, and Au-Pd. The metal-doped MOFs are shown to be highly efficient for a variety of chemical conversions, e.g., carbon-carbon couplings, and aerobic oxidation of alcohols and cyclohexane, under mild conditions. In order to encapsulate metal NPs within MOFs, we have developed a novel synthesis strategy through ligand design prior to MOF assembly, achieving uniformly distributed metal NPs inside the cavities of MOFs. This strategy can avoid the different diffusion resistance between external and internal surfaces, and thus allow metal precursors to be easily deposited into the pores and evenly distributed within the MOF networks. Moreover, we have developed a facile, rapid, and efficient strategy for the encapsulation of ultrafine Pd, Ni, and PdNi alloy inside the matrices of MOFs via in situ incorporation of metal precursors. Furthermore, we have developed a hydrophilicity-directed approach (HDA) to encapsulate large guest molecules beyond the aperture size limitation in the nanospace of MOFs, as exemplified by the self-assembly of a metal−organic polyhedral (MOP) M6L4 into MIL-101.

On the other hand, taking advantage of their ordered structures and relatively low thermal stability, MOFs could be utilized for the preparation of new metal oxides or carbon nanomaterials by thermal decomposition. In MOFs, the highly ordered metal ions are isolated by organic ligands regularly, which will play an important role in preventing metal from aggregation during thermolysis. Here we show that Co nanoparticles embedded in nitrogen-doped carbon prepared from MOFs thermonlysis could catalyze a variety of organic transformations, such as aerobic oxidation of alcohols to esters, low-temperature CO oxidation, and oxidative amidation of aldehydes.

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