B-Site Fe-Mn Bimetallic Synergy in Perovskites Drives Efficient Steam Decoking via Oxygen Vacancy Engineering

Coke deposition is a key obstructive problem to be solved in the production of ethylene via steam cracking; moreover, the removal of graphitic carbon in coke is particularly difficult. A strategy integrating Fe-Mn bimetallic synergy at the B-site with oxygen vacancy engineering in perovskites was proposed to accelerate the catalytic conversion of coke/graphitic carbon via steam. DFT simulations and experimental results revealed that Mn incorporation induces dynamic lattice reconstruction of SrFeO₃, generating abundant oxygen vacancies that enhance oxygen ion mobility and H₂O adsorption. The interaction between Fe and Mn atoms has been observed to narrow the band gap, strengthen the hybridization of the O-2p and Fe-3d orbitals, induce electron delocalization, regulate the transfer of electrons from surrounding atoms to the adsorbed oxygen species, and thus accelerate the desorption and activation of *OH and the transfer of *O^2-, which provides the possible reaction pathway for the transformation of graphitic carbon into CO or CO₂. At 900 °C, the conversion of graphitic carbon and coke with steam catalyzed by SrFe_0.1Mn_0.9O₃ reached 60.61% and 99.87%, respectively. This study provides an active material that facilitates the in situ online decoking strategy for catalytic coatings on steam cracking furnace tubes along with theoretical insights into the underlying reaction mechanism.