In situ encapsulated subnanometric CoO clusters within silicalite‐1 zeolite for efficient propane dehydrogenation

Abstract

AbstractCobalt‐based catalysts are promising alternatives to replace Pt‐ and Cr‐based catalysts for propane dehydrogenation (PDH). However, the sintering and reduction of unstable Co sites cause fast deactivation. Herein, the ultrasmall cobalt oxide clusters encapsulated within silicalite‐1 zeolites (CoO@S‐1) has been obtained via a ligand assistance in situ crystallization method. This CoO@S‐1 catalyst exhibits an attractive propylene formation rate of 13.66 mmolC3H6·gcat−1·h−1 with selectivity of >92% and is durable during 120‐h PDH reaction with five successive regeneration cycles. The high PDH activity of CoO@S‐1 is assigned to the encapsulated CoO clusters are favorable for propane adsorption and can better stabilize the detached H* species from propane, leading to the lower dehydrogenation barriers than framework Co2+ cations and Co3O4 nanoparticles. Additionally, the π‐binding propylene on CoO clusters can prevent the over‐dehydrogenation reaction compared with the di‐σ binding propylene on metallic Co, leading to the superior propylene selectivity and catalytic stability.