Low-Cost Fe-Based Oxygen Carrier Materials for the iG-CLC Process with Coal. 1

Different low-cost materials, especially Fe-based minerals or industrial residues, have been tested as carriers for iG-CLC. This work presents a methodology for the comparison of potential oxygen carriers. The methodology is based on results obtained in a batch fluidized bed reactor. The experiments were designed so that estimated solids inventory in the fuel reactor could be calculated for each oxygen carrier at different conditions and later compared. In the present paper, which is the first of a series of two, experimental results for different Fe-based materials were obtained. The second paper focuses on the evaluation and the comparison of the carriers based on these experimental results. In the present work, the performance of two iron minerals (hematite based and copper ferrite) is analyzed and compared to the behavior of ilmenite and a bauxite waste. The performance of a highly reactive synthetic Fe-based material is evaluated for comparison. In the TGA, the reactivity of the different materials to H-2, CO, CH4, and O-2 was studied. In the experiments in a fluidized bed, several O/C molar ratios were used to evaluate its effect on char gasification rate and combustion efficiency of the gasification products. The char gasification rate decreased when the O/C molar ratio decreased as the concentration of H-2 and CO in the bed increased and high levels of these gases inhibit char gasification. With no inhibitory effect, the char gasification rate was very similar. Both the bauxite waste and the hematite based mineral were able to burn the gasification products with high combustion efficiencies, comparable to those obtained in the same conditions using the synthetic Fe-based material.