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

Nanoparticles of FeOx dispersed on ceria exhibit unique chemical and textural properties. They undergo a dynamic FeOx <-> 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 FeOx clusters under the high temperature CO2 hydrogenation process. The wetting phenomenon, maximizing the density of FeOx particles on the CeO2 support, benefits from strong oxide-oxide (Fe-O-Ce) interactions.