Cobalt(II) Nanoclusters Incorporated in Ordered Mesoporous Al2O3 for Stable and Coke-Resistant Propane Dehydrogenation

High Resolution Image Download MS PowerPoint Slide 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 Co 2+ nanoclusters (Co- m -Al 2 O 3 ) via an evaporation-induced self-assembly synthesis route is presented. The ordered mesoporous alumina is characterized for containing a large amount of defective pentacoordinate Al 3+ sites and a small amount of strong acid sites. The incorporation of Co 2+ clusters within the m -Al 2 O 3 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-Al 2 O 3 catalyst. Furthermore, Co- m -Al 2 O 3 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.