Active-Site Relay of Y-Doped LaFeO3 for Enhanced CH4 Reactivity in Chemical Looping Dry Reforming of Methane

Abstract

Abstract The development of high-performance oxygen carriers (OCs) for chemical looping dry reforming of methane (CLDRM) is often hindered by the sluggish kinetics of C–H bond activation and the susceptibility to carbon deposition. Herein, we report that A-site Y doping in LaFeO3 (La0.9Y0.1FeO3) perovskite significantly enhances methane reactivity, achieving a CH4 conversion of 93–98% and a syngas yield nearly twice that of pristine LaFeO3, alongside an ideal H2/CO ratio (1.97–1.99) and stable performance at 900 °C over 30 CH4/CO2 redox cycles. Experimental and DFT analysis reveal a two-stage “active-site relay” activation mechanism. Initially, Y doping in the perovskite induces lattice distortion and enlarges Fe–O–Fe bond angles, which boosts lattice oxygen mobility and facilitates surface C–H bond cleavage. Subsequently, deep reduction triggers the in situ exsolution of metallic Fe0 nanoparticles, serving as highly active secondary centers for CH4 dissociation. The synergistic effect between exsolved Fe0 and the Y-doped perovskite with high mobility of lattice oxygen ensures rapid coke elimination, thereby enabling good cyclic stability. The strategy of the “active-site relay” can provide principles for rationally designing advanced OCs.