Conversion of CO2 on a highly active and stable Cu/FeOx/CeO2 catalyst: tuning catalytic performance by oxide-oxide interactions

Abstract

Nanoparticles of FeO_x dispersed on ceria exhibit unique chemical and textural properties. They undergo a dynamic FeO_x ↔ Fe transformation depending on the reaction conditions. The high density Fe oxide clusters dispersed over CeO₂ are effective texture promoters that enhance the stability of Cu/CeO₂ catalyst in the high temperature reverse water gas shift reaction. At the optimal Fe loading, the deactivation rate constant of a 5Cu1.6Fe/CeO₂ catalyst is only 0.003 h⁻¹, five times smaller than that of the monometallic 5Cu/CeO₂ catalyst. In situ XRD, AP-XPS and XAFS characterizations reveal that the partially reduced Fe nanoparticles would be oxidized by CO₂ in the reductive atmosphere and re-disperse into high density FeO_x clusters under the high temperature CO₂ hydrogenation process. The wetting phenomenon, maximizing the density of FeO_x particles on the CeO₂ support, benefits from strong oxide-oxide (Fe–O–Ce) interactions.