Thursday, November 12, 2015: 10:35 AM
250E (Salt Palace Convention Center)
Chemical-looping dry (CO2) reforming (CLDR) technology has been proposed which utilizes CO2 as oxidant instead of air or steam to replenish reduced oxygen carrier (OC) with oxygen. The challenge of CLDR lies in the low oxidation degree of OC and slow oxidation rate due to the weaker oxidation ability of CO2 compared to air and steam. Moreover, it is also critical to select appropriate OC materials that favor partial oxidation of CH4 (POM) for syngas production. In this regard, the aim of this study is to use CeO2 and/or La2O3 for catalyzing Fe2O3-Al2O3 based CLDR. The OCs were prepared via ultrasonication and freeze-drying assisted co-precipitation (UFDAC) method. The reaction performance of all the composite OCs was carried out in a fixed-bed reactor under atmospheric pressure condition by periodically switching CH4 and CO2. The influencing factors, including temperature, time-on-stream (TOS) and number of cycles were investigated. The characteristics of OCs were checked with Brunauer-Emmett-Teller (BET) analysis, X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS) and transmission electron microscopy (TEM). The reducibility, basicity and oxidation ability of the composite materials were elucidated with temperature-programmed reduction by H2 (H2-TPR) and CH4 (CH4-TPR), temperature-programmed desorption of CO2 (CO2-TPD) and temperature-programmed oxidation of CO2 (CO2-TPO), respectively. Experimental results suggest that the simultaneous presence of CeO2 and La2O3 can not only enhance the selectivity of Fe2O3-Al2O3 toward POM and its oxygen releasing rate for fast reaction kinetics, but also improve the reactivity of the reduced OC toward CO2 splitting reaction (CSR).