Development and Performance Evaluation of Cost-Effective Oxygen Carriers

Chemical looping combustion (CLC) for power generation has the inherent potential of enriching CO₂ from flue gases in-situ with low energy penalty compared to other commercial available options. However, the feasibility of applying CLC to burning coal is heavily depended on the suitability of oxygen carrier (OC). The ideal OCs shall present high reactivity, high resistance to attrition, no agglomeration at high temperature, cost-effective, and low secondary environmental impact. University of Kentucky Center for Applied Energy Research (CAER), which focuses on developing advanced CLC of solid fuel for large-scale power generation, has been devoting to development of cost-effective OCs using Fe-based materials. The purpose of present research is to investigate the potential of red mud [residue (waste) from alumina production] to produce cost-effective OCs for coal-fueled CLC and to obtain its performance for comparison with Fe-based OCs. The OC samples used are made from red mud that contains 33wt% Fe-element by freeze granulation (FG) methods. In preliminary study, the reductivity and oxygen transport capacity of red mud OCs produced from different sintering temperatures (1000 ^oC-1200^oC) and times were tested in a thermogravimetric analyzer coupled with a mass spectrometer (TG-MS) using gaseous fuel as reduction agent. The BET surfaces, SEM imagines, mechanical strengths and agglomeration temperature of these red muds OCs were obtained. The performance of the red mud OCs was compared with that of OCs from commercially available Fe₂O₃ and α-alumina powders. The results showed that it is feasible to produce cost-effective Fe-based OCs from red mud with similar performance as the OC prepared from 50% Fe₂O₃and 50% α-alumina powders.