Reaction schemes of barium ferrite in biomass chemical looping gasification for hydrogen-enriched syngas generation via an outer-inner looping redox reaction mechanism

The objective of this study was to build an efficient outer-inner looping redox reaction mechanism called steam recycled biomass chemical looping gasification (SR-BCLG) for H-2 production by using BaFe2O4 as an oxygen carrier (OC). The X-ray diffraction (XRD) results showed the phase changes of BaFe2O4 in the SR-BCLG process can be oxidized to its initial state stimulated by steam. In addition, the impacts on the temperature, water injection rate (steam/biomass ratio) and OC loading were investigated. The maximum H-2 production of 28.5 mol/kg(.) biomass was achieved in the 60 min of gasification with a BaFe2O4 load amount of 10 wt%, which is an increase in H-2 production of 109.6% compared with the no-OC biomass gasification process under the optimal conditions. Durative high production of H-2-enriched syngas was obtained during the cyclic stability tests, indicating the significant redox durability and high H-2-generation properties of BaFe2O4. The XRD, scanning electron microscopy (SEM), and thermo-gravimetric analyzer (TG) characterizations revealed the high stability of BaFe2O4, which can be ascribed to the existence of Ba2+. The bimetal functional BaFe2O4 allows for an innovative method of outer-inner looping redox reactions for continuous H-2-enriched syngas generation in the SR-BCLG process.