CATALYSTS PREPARED BY CONFINING METAL NANOCLUSTERS IN METAL ORGANIC FRAMEWORKS

摘要

Metal–organic frameworks (MOFs) have been investigatedrnextensively because of their high surface areas, well-definedrnporosities and chemical tenability. In recent years, MOFs haverndemonstrated their great potential application as heterogeneousrncatalysts, especially those using MOFs as a supporting matrix forrnmetal nanoparticles (known as metal@MOFs). However, to confinernmetal nanoclusters in the cavities of MOFs is difficult. Herein, wernused amine groups on the linkers of MOFs to coordinate metalrnprecursors, which lead to a metal@MOF catalyst with extremelyrnmonodisperse metal nanoclusters after reduction. We carefullyrnexamined the confinement of metal nanoclusters in the MOF usingrnTEM by tilting the specimen at different angles. We also used probernmolecules to confirm that metal nanoclusters are confined by thernMOF. These MOF confined metal nanoclusters showed interestingrncatalytic properties, which will be discussed in this presentation.rnWe tested the importance of confining NPs inside the cage ofrnMOFs and its application in chemical reactions. We found that bothrnhigh selectivity to cinnamyl alcohol and high conversion ofrncinnamaldehyde can be achieved using the MOF-confined Ptrnnanoclusters catalyst, while we could not achieve high cinnamylrnalcohol selectivity on Pt NCs supported on the external surface of thernMOF. The catalyst can be recycled ten times without any loss in itsrnactivity and selectivity. To confirm the stability of the recycledrncatalysts, we conducted kinetic studies for the first 20 hours ofrnreaction during four recycle runs on the catalyst. Both the conversionrnand selectivity are almost overlapping for the four runs, whichrnindicates the catalyst is very stable under the employed reactionrnconditions.