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

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.