Ultra-durable Ni-Ir/MgAl₂O₄ catalysts for dry reforming of methane enabled by dynamic balance between carbon deposition and elimination

Carbon deposition is the main cause for the catalyst deactivation of methane dry reforming, and researchers are committed to exploring effective catalyst systems with zero carbon deposition in order to achieve a practically long lifetime. In this work, we propose an equilibrium theory with matched rates of CH₄ dissociation and CO₂ activation to establish a balance between carbon deposition and carbon elimination and construct highly dispersed Ni-Ir/MgAl₂O₄ alloy catalysts accordingly, where Ni activated CH₄, MgAl₂O₄ adsorbed CO₂ to form surface carbonates, and Ir effectively used the carbonates to eliminate carbon species generated by CH₄ dissociation. Theoretical assessment further unveiled that the preferred CO₂ activation on Ir over Ni is derived from its stronger oxophilicity. With an optimal Ni/Ir atomic ratio of 1/2, high activity and long-period stability (600 h) with zero carbon deposition were obtained concurrently for dry reforming of methane at industrially relevant temperature (650°C).