Synthesis gas production through biomass direct chemical looping conversion with natural hematite as an oxygen carrier

Biomass direct chemical looping (BDCL) conversion with natural hematite as an oxygen carrier was conducted in a fluidized bed reactor under argon atmosphere focusing on investigation the cyclic performance of oxygen carrier. The presence of oxygen carrier can evidently promote the biomass conversion. The gas yield and carbon conversion increased from 0.75 Nm3/kg and 62.23% of biomass pyrolysis to 1.06 Nm3/kg and 87.63% of BDCL, respectively. The components of the gas product in BDCL were close to those in biomass pyrolysis as the cyclic number increased. The gas yield and carbon conversion decreased from 1.06 Nm3/kg and 87.63% at 1st cycle to 0.93 Nm3/kg and 77.18% at 20th cycle, respectively, due to the attrition and structural changes of oxygen carrier. X-ray diffraction (XRD) analysis showed that the reduction extent of oxygen carrier increased with the cycles. Scanning electron microscope (SEM) and pore structural analysis displayed that agglomeration was observed with the cycles.