Reaction-induced restructuring of CoOx species to control selectivity in propane dehydrogenation

Propene is one of the most important basic petrochemicals widely used for the production of polypropylene, solvents, acrylic acid, etc. The conventional routes for the manufacture of this building block include steam or fluid catalytic cracking of different oil fractions, methanol to olefin and non-oxidative propane dehydrogenation (PDH). The PDH approach has been attracting increasing attention because of the shale gas revolution. This reaction is carried out on a large scale using highly expensive or environmentally unfriendly Pt- or Cr-containing catalysts. Co-based catalysts are of particular interest due to their excellent ability to selectively activate C-H bonds in various alkanes.

It is, however, worth mentioning that the kind of the active species (Co0, Co2+ or Co3O4) responsible for the formation of propene in the PDH reaction is still controversially discussed in literature. Isolated Co2+Ox species on the surface of SiO2, Al2O3 or zeolites are widely accepted to be required for the desired reaction, while metallic Co0 species catalyze cracking reactions of propane and coke formation. However, other studies suggest that the highly dispersed Co0 species formed in situ from CoOx dehydrogenate propane to propene selectively. A few efforts have been made to understand the role of metallic Co0 in the PDH reaction.

Recently, a research team led by Prof. Evgenii V. Kondratenko from Leibniz-Institut für Katalyse e.V., Germany presents reaction-induced restructuring of CoOx species supported on silicalite-1(S-1) zeolite and its consequences for catalyst activity and, in particular, product selectivity in the PDH reaction. The lattice oxygen of oxidized CoOx can oxidize propane not only to propene but also to carbon oxides. The larger the CoOx species, the more important the latter reaction. Due to the limited amount of lattice oxygen species, these oxidation reactions proceed during a few first seconds on propane stream under PDH conditions. The propane-mediated reduction of CoOx results in the formation of Co0 species, which are, however, highly active for the conversion of propane to carbon-deposits, methane, and hydrogen but not to propene. To favor the latter reaction, small Co0 species must be decorated by a carbon-containing layer, which simply covers the sites for the deep dehydrogenation and cracking reactions and/or changes the electronic state of Co0 species requiring for the efficient dehydrogenation of propane to propene. The results were published in Chinese Journal of Catalysis.

The results were published in Chinese Journal of Catalysis (DOI: 10.1016/S1872-2067(25)64724-3)

About the Journal

Chinese Journal of Catalysis is co-sponsored by Dalian Institute of Chemical Physics, Chinese Academy of Sciences and Chinese Chemical Society, and it is currently published by Elsevier group. This monthly journal publishes in English timely contributions of original and rigorously reviewed manuscripts covering all areas of catalysis. The journal publishes Reviews, Accounts, Communications, Articles, Highlights, Perspectives, and Viewpoints of highly scientific values that help understanding and defining of new concepts in both fundamental issues and practical applications of catalysis. Chinese Journal of Catalysis ranks among the top one journals in Applied Chemistry with a current SCI impact factor of 17.7. The Editors-in-Chief are Profs. Can Li and Tao Zhang.

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