Observations of steam chemical-looping gasification using hematite (iron oxide, hematite) and Illinois basin coals

Previous research in the field of chemical-looping combustion has laid a solid foundation for studying metal oxide interaction with coal. This study was conducted to observe the potential of hematite (Iron oxide, Fe2O 3) to regulate the formation of gaseous hydrogen (H2) and carbon species including methane (CH4), carbon monoxide (CO), and carbon dioxide (CO2) to improve chemical-looping steam gasification for two Illinois Basin coals. The batch reaction method selected for experimentation models the metal oxidation and coal steam gasification phase of the chemical-looping gasification process. After a review of the pertinent literature and thermodynamic chemical modeling software, a weight ratio of hematite to coal of 30:1 was physically mixed with coal and gasified in the presence of steam at 800, 850, and 900°C. The ratio of water to coal was 2:1 by weight. The greatest carbon conversion (above 95%) to gaseous carbon species was observed at 900°C for both Illinois Basin coals during a 16 minute residence time. Surplus water formation was also observed in all phases of the study. Total conversion of CO and CH4 to CO2 was not achieved, and the presence of H2 in the product gas yield indicates a depletion of usable iron-based oxygen during reaction. It is recommended the study be continued under a fluidized bed to improve the efficiency of chemical contact reactions between solids and gases. Thermo-Gravinimetric Analysis of residues should be included with future studies to quantify the presence of iron oxide species. Also, the formation of steam should be quantified.