Suppressing Metallic Co⁰ Formation in Co-Based Catalyst by In-Situ Selective H₂ Oxidation for Efficient Ethane...

Cobalt-based catalysts are attractive for ethane dehydrogenation owning to their high ethane activation activity. However, in the H₂-rich environment generated during the reaction, cobalt species are readily reduced to metallic Co⁰, leading to coke deposition and catalyst deactivation. Here, we present a tandem strategy that integrates a CoO_x/HZSM-5 (Co/HZ) dehydrogenation catalyst with CeO₂-promoted Bi₂O₃ (CeBiO_x) as a selective H₂ oxidation oxygen carrier. Under chemical looping oxidative dehydrogenation (CL-ODH) conditions, CeBiO_x selectively oxidizes over 75% of the in-situ generated H₂, thereby effectively suppressing the formation of metallic Co⁰ in Co/HZ. As a result, an ethane conversion of 40% and an ethylene selectivity exceeding 80% are achieved at 600°C, with stable performance maintained over 100 redox cycles. Pulse reaction experiments, semi in-situ characterizations, and density functional theory (DFT) calculations collectively reveal that the selective oxidation of H₂ by CeBiO_x inhibits the reduction of cobalt species to Co⁰, thereby mitigating coke formation and enhancing ethylene yield. By coupling an ethane dehydrogenation catalyst with a selective H₂ oxidation oxygen carrier, this work establishes a new paradigm for stabilizing active Co species in Co-based ethane dehydrogenation systems and intensifying ethylene production.