Fine-Tuning the Activity of Metal-Organic Framework-Supported Cobalt Catalysts for the Oxidative Dehydrogenation of Propane

Zhanyong Li, Aaron W. Peters, Ana E. Platero-Prats, Jian Liu, Chung Wei Kung, Hyunho Noh, Matthew R. DeStefano, Neil M. Schweitzer, Karena W. Chapman, Joseph T. Hupp, Omar K. Farha

研究成果: Article同行評審

79 引文 斯高帕斯(Scopus)

摘要

Few-atom cobalt-oxide clusters, when dispersed on a Zr-based metal-organic framework (MOF) NU-1000, have been shown to be active for the oxidative dehydrogenation (ODH) of propane at low temperatures (<230 °C), affording a selective and stable propene production catalyst. In our current work, a series of promoter ions with varying Lewis acidity, including Ni(II), Zn(II), Al(III), Ti(IV) and Mo(VI), are anchored as metal-oxide,hydroxide clusters to NU-1000 followed by Co(II) ion deposition, yielding a series of NU-1000-supported bimetallic-oxo,hydroxo,aqua clusters. Using difference envelope density (DED) analyses, the spatial locations of the promoter ions and catalytic cobalt ions are determined. For all samples, the promoter ions are sited between pairs of Zr6 nodes along the MOF c-axis, whereas the location of the cobalt ions varies with the promoter ions. These NU-1000-supported bimetallic-oxide clusters are active for propane ODH after thermal activation under O2 to open a cobalt coordination site and to oxidize Co(II) to Co(III), as evidenced by operando X-ray absorption spectroscopy at the Co K-edge. In accord with the decreasing Lewis acidity of the promoter ion, catalytic activity increases in the following order: Mo(VI) < Ti(IV) < Al(III) < Zn(II) < Ni(II). The finding is attributed to increasing ease of formation of Co(III)-O species and stabilization of a cobalt(III)-oxyl/propane transition state as the Lewis acidity of the promoter ions decreases. The results point to an increasing ability to fine-tune the structure-dependent activity of MOF-supported heterogeneous catalysts. Coupled with mechanistic studies - computational or experimental - this ability may translate into informed prediction of improved catalysts for propane ODH and other chemical reactions.

原文English
頁(從 - 到)15251-15258
頁數8
期刊Journal of the American Chemical Society
139
發行號42
DOIs
出版狀態Published - 2017 十月 25

All Science Journal Classification (ASJC) codes

  • 催化
  • 化學 (全部)
  • 生物化學
  • 膠體和表面化學

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