(24c) Solar Thermochemical Conversion of CO2 Using Co-Precipitation Synthesized CexNiyMzO2-X (where M = transition metal cations)

Authors: 
Bhosale, R. - Presenter, Qatar University
Takalkar, G., Qatar University
Rashid, S., Qatar University
One of the most appealing options for the production of H2 or syngas is the metal oxide-based solar thermochemical H2O/CO2 splitting cycle. In this redox process, the fuel production can be achieved at lower operating temperatures as compared to the direct thermolysis. This two-step process involves successive reduction and re-oxidation of the metal oxides in the presence of concentrated solar power resulting in the production of O2 and H2/syngas in separate steps. Among the various metal oxides investigated until now, ceria based redox materials are considered as a very good option due to their high thermal stability and faster kinetics. To improve the redox reactivity, the ceria fluorite structure is doped with different metal cations and further investigated towards thermochemical water-splitting reaction. The findings of these studies confirm improvement in the thermal reduction and water splitting ability of the doped ceria materials as compared to pure ceria. In one such case, catalytic CexNi1-xO2-δ redox materials are examined for thermochemical H2O splitting reactions, however, their ability to produce CO via CO2 splitting reaction is not much studied. For the production of high-quality syngas, in addition to H2, the production of CO via CO2 splitting is also essential. Therefore, in this study, the thermochemical CO2 splitting ability of the CexNi1-xO2-δ and CexNiyMzO2-δ (where M = transition metal cations) catalytic materials was investigated by performing multiple thermal reductions and CO2 splitting cycles. The derived materials were analyzed using powder x-ray diffractometry (PXRD), scanning electron microscopy (SEM), and BET surface area analyzer (BET). These ceria materials were further tested towards multiple thermochemical CO2 splitting reactions by using a high-temperature thermogravimetric analyzer. The results obtained indicate significant improvement in the fuel production capacity and thermal stability of these catalytic materials.