La2–xSrxCe2–yNiyO7Catalysts with Interstitial Nickel for Enhanced Dry Reforming of Methane

Abstract

This study explores the catalytic performance of solution combustion-synthesized doped defective fluorite catalysts, La2–xSrxCe2–yNiyO7, for the dry reforming of methane. A comprehensive structural analysis, supported by theoretical calculations, revealed that the adopted synthetic methodology enabled Ni doping beyond a critical concentration, leading to its occupation of the interstitial lattice sites. The optimally doped Ni-containing defective fluorite oxide La1.9Sr0.1Ce1.7Ni0.3O7exhibited superior catalytic activity with more than 70% conversion of CO2and CH4with an H2/CO ratio of 0.7 for a 50-h reaction at 700 °C. The prolonged reforming reaction also resulted in minimal coke deposition (11 μgcgcat–1h–1), primarily due to the oxidative dissociation pathway of methane, as revealed through mechanistic analysis. Detailed surface studies highlighted the crucial role of metal–support interactions, wherein facile electron transfer from Ni to Ce during the reaction contributed significantly to the enhanced catalytic performance. Thus, this study establishes a strategic framework for designing and developing defect-engineered oxide catalysts, paving the way for advanced materials in dry methane reforming.