Synthesis gas generation by chemical-looping gasification of biomass using natural hematite as oxygen carrier

The chemical looping gasification (CLG) of biomass with natural hematite (Fe₂O₃) as oxygen carrier was experimentally investigated in a bubbling fluidized bed reactor using argon as fluidizing gas. The effects of reaction temperature, resistance time, and the presence of oxygen carrier on the syngas composition, gas yield, carbon conversion, and gasification efficiency were examined. The experimental results show that the natural hematite can be used as oxygen carrier in CLG of biomass. The concentration of CO and H₂ increases slightly, while that of CO₂ and CH₄ declines slightly with the increasing of temperature during biomass gasification. In addition, the concentration of H₂, CO, and CH₄ in the syngas slowly increases with the reaction time, but CO₂ concentration shows an opposite trend. The presence of oxygen carrier can significantly increase the gas yield and carbon conversion. The analysis by Scanning electron microscopy-Energy Disperse Spectroscopy (SEM-EDS) shows that the iron ore oxygen carrier is obviously sintered when the reaction temperature is greater than 850 ℃. However, the composition of element on the particle surface changes little during the reaction.