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 degrees C).