(60a) High Temperature Oxygen Carrier for Chemical Looping Combustion: Case Study Comparison between Canadian Hematite and Iron on a FCC Support

Authors: 
Hammache, S., National Energy Technology Laboratory
Means, N. C., National Energy Technology Laboratory
Burgess, W. A., National Energy Technology Laboratory
Smith, M., National Energy Technology Laboratory
Shekhawat, D., National Energy Technology Laboratory
Howard, B. H., National Energy Technology Laboratory
High temperature oxygen carrier for chemical looping combustion: case study comparison between Canadian hematite and iron on a FCC support

Sonia Hammache1,3, Nicholas Means1,3, Ward Burgess1,3, Mark Smith2, Dushyant Shekhawat2, and Bret Howard1

1National Energy Technology Laboratory, United States Department of Energy, Pittsburgh, PA, USA

2National Energy Technology Laboratory, United States Department of Energy, Morgantown, WV, USA

3AECOM, 626 Cochran Mills Rd, Pittsburgh, PA, USA

Chemical Looping Combustion (CLC), in which oxygen carrier materials oxidize a fuel to produce CO2 and water, can provide a pathway for energy generation with easier carbon capture. However, the cost and stability of the oxygen carrier material remain a significant barrier to successful commercial implementation. This study will investigate the stability of Canadian hematite in a laboratory scale drop-tube fixed bed reactor. Activity, as determined by the oxygen released from the oxygen carrier during the reduction phase, decreased over the initial three to five reduction/oxidation cycles before stabilizing. After 50 cycles, the spent sample showed significant agglomeration and surface cracking. The oxidation of the oxygen carrier during the regeneration phase rapidly released thermal energy, leading to sintering of the material. A sample, calcined at 1100 oC before use, showed a complementary trend, with initial lower activity increasing to approach a similar plateau after several cycles. Iron oxide supported by FCC, a spent FCC catalyst, was also studied. Fe/FCC showed a similar degradation caused by sintering, but also showed reduced activity due to an Fe interaction with the support which resulted in formation of iron aluminate and iron silicate. Sample characterization included SEM, X-ray diffraction, and N2 physisorption. These results and results for other oxygen carriers will be discussed.