Single Co Sites in Ordered SiO₂ Channels for Boosting Nonoxidative Propane Dehydrogenation

Searching for low-cost, environmentally friendly, and highly active catalysts for C-H bond activation in propane dehydrogenation (PDH) reaction remains a great challenge. Herein, SiO₂ nanomeshes (NMs) with ultrashort three-dimensional (3D) channels were constructed to effectively confine the Co single atoms (Co SAs/SiO₂ NMs). The ultrashort 3D channels were formed by gasifying carbon in the self-assembled SiO₂@polymer composites under the air atmosphere. The carbon removal process resulted in abundant oxygen (O*) defects in the channel windowsill that immobilized the dissociative Co₁ species to afford the sintering-resistant Co SAs/SiO₂ NMs catalyst. The as-obtained Co SAs/SiO₂ NMs with unsaturated Co-O₃ sites exhibited an outstanding PDH catalytic behavior (95% selectivity and 196 h^-1 turnover frequency), superior to Co SAs/SiO₂ commerce (83%, 49 h^-1), Co NPs/SiO₂ NMs (87%, 13 h^-1), and most non-noble metal-based catalysts. Furthermore, Co SAs/SiO₂ NMs showed high long-term stability with no significant deactivation during 24 h of reaction. Theoretical and experimental analysis indicated that these unsaturated Co-O₃ sites could selectively activate the first and second C-H bonds and limit the further splitting of C-H (C) bonds during PDH. This work paves a way for designing high-efficiency single-atom catalysts for PDH.