(46b) Investigation of Bimetallic Mn-Fe Oxygen Carriers for Coal in Situ Gasification Chemical-Looping Combustion (iG-CLC)

Means, N. C., National Energy Technology Laboratory
Howard, B. H., National Energy Technology Laboratory
Shekhawat, D., US Dept of Energy
Bimetallic Mn-Fe oxygen carriers are investigated for coal in situ Gasification Chemical-Looping Combustion (iG-CLC) process in this study. Both manganese oxide and iron oxide have low toxicity, low cost and are easily available raw materials. The combined Mn-Fe OC has potential to overcome the disadvantages of Fe based OCs such as slow reaction rate and low oxygen transport capability and could also improve the attrition problems of Mn-based OCs. The Mn-Fe OC with an inert dispersant of silicon dioxide (SiO2) was prepared by pelletizing the components with a hydraulic press followed by calcination. Reactivities of the OCs with coal char and their CO2 capture efficiency were investigated at selected temperatures (up to 1100°C) under gasification conditions. Produced gas compositions were measured using mass spectrometery (MS) to evaluate CO2 capture efficiency. The Mn and Fe compounds present in fresh OCs and their test residues were determined using XRD. Thermal oxygen uncoupling of the OC, releasing gaseous O2, was evaluated for the Mn2O3/Mn3O4 redox system. Results show high reactivity and CO2 capture efficiency for the combined Mn-Fe OC on reduction with coal char. Results suggest Mn-Fe has potential as an oxygen carrier for coal iG-CLC.