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Abstract:
Due to their availability, low cost, and activity, cobalt-based catalysts are a promising alternative to platinum for the industrial propane dehydrogenation processes. However, their low stability due to sintering, phase transformation, and coke deposition leads to severe deactivation. In this work, the synthesis of amorphous, ordered mesoporous alumina with stabilized Co2+ nanoclusters (Co-m-Al2O3) via an evaporation-induced self-assembly synthesis route is presented. The ordered mesoporous alumina is characterized for containing a large amount of defective pentacoordinate Al3+ sites and a small amount of strong acid sites. The incorporation of Co2+ clusters within the m-Al2O3 structure enhances the dispersion and stability and preserves their reduction even after prolonged time on stream. This leads to a highly selective and steady catalytic performance in the propane dehydrogenation reaction under industrial-relevant conditions. A significantly low deactivation rate of 0.53 d–1 with stable propylene selectivity of 95% is observed after 23 h, resulting in a 117% higher space–time yield toward propylene compared to the state-of-the-art impregnated Co/γ-Al2O3 catalyst. Furthermore, Co-m-Al2O3 leads to 4.6 times less coke formation, measured in situ for the first time. The detailed study of the nature of the cobalt sites, together with the acidic properties of the alumina supports, provides a deeper understanding of cobalt-based catalysts for dehydrogenation reactions.
