A novel biomass gasification process for the generation of inherently separated syngas using the concept of chemical looping technology

Biomass-based hydrogen generation has been showing a potential prospect in solving the global environment and energy challenges. This study introduces a novel chemical looping system, known as chemical looping partial oxidation and hydrogen generation (CLPH) process, which can generate inherently separated syngas from biomass, thus presenting a good application prospect. The feasibility of this system and the selection of appropriate oxygen carriers (OCs), which were the key to the success of this system, were investigated in this work. Four MFe2O4 (M=Ni, Co, Ca, Ba) OCs were chosen according to the modified Ellingham diagram, and their performances as well as the reaction pathway of BaFe2O4 and C were comprehensively investigated. The results show that all OCs exhibit a good solid-solid reactivity, but the CO selectivity of CaFe2O4 and BaFe2O4 (around 60%) are higher than that of CoFe2O4 and NiFe2O4 (around 20%). Additionally, the cycle performance of CaFe2O4 is worse than that of BaFe2O4, which is owing to the poor self-healing property. Thus, BaFe2O4 was chosen as the ideal OC for the CLPH process. A successful biomass gasification process for the generation of inherently separated syngas was developed, achieving a carbon conversion rate of 93%, CO selectivity of ≥ 60%, wonderful hydrogen yield of ≥ 1700 mL/g·biomass char and hydrogen purity of ≥ 94% over 5 cycles.