Controlling Ni-Fe Exsolution in Perovskite Oxygen Carriers for Enhanced Chemical Looping Dry Reforming of Methane

Abstract

Chemical looping dry reforming of methane (CL-DRM) is a novel CO₂ utilization technology, producing high-quality syngas. Herein, the perovskite oxygen carriers La(Fe_0.8-xNi_xAl_0.2)O₃ (x = 0, 0.2, 0.4, 0.6, and 0.8) were investigated for the CL-DRM process. Remarkably, La(Fe_0.4Ni_0.4Al_0.2)O₃ exhibited 93% CH₄ conversion, 100% CO₂ conversion, and 100% CO selectivity at 800 °C. Combined activity and characterization results suggest that the doping of Al promotes the nucleation of Ni and the growth of Ni-Fe nanoparticles. Owing to the redox exsolution effect during the cycles, the oxygen carriers are modified with abundant Ni-Fe catalytic sites on the surface, which exhibit excellent catalytic activity, oxygen capacity, and structural stability. In addition, the carbon cycle, which consists of methane decomposition and carbon oxidation, is catalyzed by Ni-Fe nanoparticles for enhanced CH₄ and CO₂ conversion during the cyclic redox process. We anticipate that the engineering of nanocatalytic sites on oxygen carriers will be conducive to obtaining target products for CL-DRM process optimization.