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

Abstract

Few-atom cobalt-oxide clusters, when dispersed on a Zr-based metal–organic framework (MOF) NU-1000, have previously 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 via SIM (solvothermal deposition within MOFs–specifically the nodes) followed by incorporation of Co(II) ions via vapor-phase AIM (atomic layer deposition (ALD) in MOFs). This process yields 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 SIM-anchored promoter ions are sited between pairs of Zr₆ nodes along the MOF c-axis (channel-aligned axis) whereas the location of the AIM-anchored cobalt ions varies depending on the identity of promoter metal ion. With Ni(II)-, Al(III)-, or Ti(IV)-containing clusters as promoters, the oxy-cobalt species are sited atop the promoter sites; with Mo(VI) they grow exclusively on the MOF nodes sites (hexa-Zr(IV)- oxo,hydroxo,aqua units); with Zn(II) they grow on both the node and promoter. The NU-1000- supported bimetallic-oxide clustersmore » 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 Xray absorption spectroscopy at the Co K-edge. The cobalt component is exclusively responsible for the observed catalysis. In accord with the decreasing Lewis acidity of the promoter ion, catalytic activity increases in the order: Mo(VI)« less

Authors:

Li, Zhanyong  ^[1];

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Peters, Aaron W. ^[1]; Platero-Prats, Ana E.  ^[2];

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Liu, Jian ^[1]; Kung, Chung-Wei  ^[1];

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Noh, Hyunho ^[1]; DeStefano, Matthew R.  ^[1];

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Schweitzer, Neil M. ^[3]; Chapman, Karena W.  ^[2];

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Hupp, Joseph T.  ^[1];

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Farha, Omar K.  ^[4]

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+ Show Author Affiliations

1. Northwestern Univ., Evanston, IL (United States). Dept. of Chemistry
2. Argonne National Lab. (ANL), Argonne, IL (United States). Advanced Photon Source (APS), X-ray Science Division
3. Northwestern Univ., Evanston, IL (United States). Dept. of Chemical and Biological Engineering
4. Northwestern Univ., Evanston, IL (United States). Dept. of Chemistry; King Abdulaziz Univ., Jeddah (Saudi Arabia). Dept. of Chemistry

Publication Date:

2017-10-04

Research Org.:

Argonne National Laboratory (ANL), Argonne, IL (United States); Energy Frontier Research Centers (EFRC) (United States). Energy Frontier Research Center for Inorganometallic Catalyst Design (ICDC)

Sponsoring Org.:

USDOE Office of Science (SC), Basic Energy Sciences (BES); USDOD; ational Science Foundation (NSF); Ministry of Economy and Knowledge from the Catalan Government; Ministry of Science and Technology (Taiwan)

OSTI Identifier:

1419945

Grant/Contract Number:  

AC02-06CH11357; SC0012702

Resource Type:

Accepted Manuscript

Journal Name:

Journal of the American Chemical Society

Additional Journal Information:

Journal Volume: 139; Journal Issue: 42; Journal ID: ISSN 0002-7863

Publisher:

American Chemical Society (ACS)

Country of Publication:

United States

Language:

English

Subject:

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY