Chinese Journal of Catalysis ›› 2025, Vol. 74: 108-119.DOI: 10.1016/S1872-2067(25)64724-3

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Understanding the reaction-induced restructuring of CoOx species in silicalite-1 to control selectivity in non-oxidative dehydrogenation of propane

Qiyang Zhanga,*(), Vita A. Kondratenkoa, Xiangnong Dinga, Jana Weissa, Stephan Bartlinga, Elizaveta Fedorovaa, Dan Zhaoa,b,c, Dmitry E. Doronkinb, Dongxu Wangd, Christoph Kubisa, Evgenii V. Kondratenkoa,*()   

  1. aLeibniz-Institut für Katalyse e.V., D-18059 Rostock, Germany
    bInstitute for Chemical Technology and Polymer Chemistry, and Institute of Catalysis Research and Technology, Karlsruhe Institute of Technology, D-76131, Karlsruhe, Germany
    cNational Engineering Laboratory for Methanol to Olefins, Dalian National Laboratory for Clean Energy, iChEM (Collaborative Innovation Center of Chemistry for Energy Materials), Dalian Institute of Chemical Physics, Chinese Academy of Sciences, Dalian 116023, Liaoning, China
    dMax Planck Institute of Microstructure Physics, 06120 Halle, Germany
  • Received:2025-01-28 Accepted:2025-03-08 Online:2025-07-18 Published:2025-07-20
  • Contact: *E-mail: Qiyang.Zhang@catalysis.de (Q. Zhang), Evgenii.kondratenko@catalysis.de (E. V. Kondratenko).

Abstract:

Non-oxidative dehydrogenation of propane (PDH) is an important route for large-scale on purpose propene production. Although cobalt-based catalysts are promising alternatives to currently used platinum- or chromium oxide-based catalysts, their further developments are hindered by the uncertainties related to the kind of the active sites involved in the desired and side reactions. To contribute to closing such a gap, we systematically investigate the role of oxidized CoOx and metallic Co0 species in the PDH reaction over catalysts based in Silicalite-1 with supported CoOx species differing in their redox properties. C3H8 pulse experiments with sub-millisecond and second resolution at pulse sizes of about 13 and 2200 nmol, respectively, combined with in-depth catalyst characterization and PDH tests at different propane conversions enabled us to understand how the reaction-induced reduction of CoOx affects product selectivity. Propane readily reacts with CoOx to yield propene, carbon oxides and water. The formed Co0 species show high activity to coking and cracking reactions. However, if the size of such species is below 2 nm, these undesired reactions are significantly hindered due to the coverage of the active sites by carbon-containing species. The remaining uncovered surface Co0 sites selectively dehydrogenate propane to propene. The best-performing catalyst showed higher activity than a commercial-like K-CrOx/Al2O3 and operated durable in a series of 10 dehydrogenation/regeneration cycles under industrial relevant conditions. The space time yield of propene formation of 0.97 kg·h-1·kgcat-1 was achieved at 550 °C, 52% equilibrium propane conversion and 95% propene selectivity.

Key words: Propane, Dehydrogenation, Propene, Cobalt, Mechanism