Malonzo Camille D, Wang Zhao, Duan Jiaxin, Zhao Wenyang, Webber Thomas E, Li Zhanyong, Kim In Soo, Kumar Anurag, Bhan Aditya, Platero-Prats Ana E, Chapman Karena W, Farha Omar K, Hupp Joseph T, Martinson Alex B F, Penn R Lee, Stein Andreas
Department of Chemistry , University of Minnesota , Minneapolis , Minnesota 55455 , United States.
Department of Chemistry , Northwestern University , Evanston , Illinois 60208 , United States.
Inorg Chem. 2018 Mar 5;57(5):2782-2790. doi: 10.1021/acs.inorgchem.7b03181. Epub 2018 Feb 20.
Nanocasting can be a useful strategy to transfer the catalytic metal clusters in metal-organic frameworks (MOFs) to an all-inorganic support such as silica. The incorporation of silica in the MOF pores as a secondary support has the potential to extend the application of the highly tunable metal-based active sites in MOFs to high temperature catalysis. Here, we demonstrate the applicability of the nanocasting method to a range of MOFs that incorporate catalytically attractive hexazirconium, hexacerium, or pentanickel oxide-based clusters (UiO-66, (Ce)UiO-66, (Ce)UiO-67, (Ce)MOF-808, DUT-9, and In- and Ni-postmetalated NU-1000). We describe, in tutorial form, the challenges associated with nanocasting of MOFs that are related to their small pore size and to considerations of chemical and mechanical stability, and we provide approaches to overcome some of these challenges. Some of these nanocast materials feature the site-isolated clusters in a porous, thermally stable silica matrix, suitable for catalysis at high temperatures; in others, structural rearrangement of clusters or partial cluster aggregation occurs, but extensive aggregation can be mitigated by the silica skeleton introduced during nanocasting.
纳米铸造可以作为一种有用的策略，将金属有机框架（MOF）中的催化金属簇转移到诸如二氧化硅之类的全无机载体上。在MOF孔中引入二氧化硅作为二级载体，有可能将MOF中高度可调的金属基活性位点的应用扩展到高温催化领域。在此，我们展示了纳米铸造方法对一系列包含具有催化吸引力的六锆、六铈或五氧化镍基簇（UiO-66、(Ce)UiO-66、(Ce)UiO-67、(Ce)MOF-808、DUT-9以及铟和镍后金属化的NU-1000）的MOF的适用性。我们以教程的形式描述了与MOF纳米铸造相关的挑战，这些挑战涉及其小孔径以及化学和机械稳定性方面的考虑因素，并提供了克服其中一些挑战的方法。其中一些纳米铸造材料在多孔、热稳定的二氧化硅基质中具有位点隔离的簇，适用于高温催化；在其他材料中，簇会发生结构重排或部分簇聚集，但纳米铸造过程中引入的二氧化硅骨架可以减轻广泛的聚集。
