Mid-temperature CO2 deoxygenation to CO over Fe-CeO2

CO 2 capture and utilization is a must for easing the global warming caused by the uses of fossil fuels. We examine M-CeO 2 (M = Cu, Co, and Fe @M/Ce = 2/8) prepared by coprecipitation and hard template synthesis. Fe-CeO 2 is the only one showing thermal CO 2 deoxygenation to CO at below 700 °C after reduction. XRD analyses of as prepared Fe-CeO 2 demonstrate the presence of segregated Fe 2 O 3 and CeO 2 phases with partial mixing. Both Fe 2 O 3 phase and CeO 2 phase show redox during sequential TPR (temperature-programmed reduction)-CO 2 -TPRx (temperature-programmed reaction) up to 700 °C. The evolved Fe 0 after TPR appears to be the main active phase for CO 2 deoxygenation which becomes oxidized back to Fe 2 O 3 after CO 2 -TPRx. The results indicate that the interface (interphase) between Fe-domain and CeO 2 -domain is involved leading to the observed deoxygenation reactivity. That the stripped oxygen from CO 2 over Fe-domain can spillover to CeO 2 domain is considered as a possible explanation. We perform isothermal CO 2 deoxygenation test at 600 °C over TPR-treated Fe-CeO 2 using oxygen-conducting membrane reactor, and the CO 2 deoxygenation capacity is found significantly higher than that observed when in the absence of oxygen conducting membrane. This demonstrates not only the possible oxygen spillover but also the possibility of achieving a sustainable CO 2 deoxygenation process. • Reduced Fe-CeO 2 shows CO 2 deoxygenation activity with an onset temperature at around 350 °C in CO 2 -TPRx. • The CO 2 deoxygenation reactivity of Fe-CeO 2 depends on the preparation method and the Fe/Ce ratio. • Segregated CeO 2 and Fe 2 O 3 phases of as-prepared Fe-CeO 2 both show redox during TPR-CO 2 -TPRx test. • In situ DRIFTS indicate bent CO 2 δ- adspecies when CO 2 deoxygenation is observed. • Fe 0 is the main active phase with spillover of the O stripped from CO 2 to CeO 2 and to oxygen-conducting membrane.