Thermodynamic equilibrium analysis of H2-rich syngas production via sorption-enhanced chemical looping biomass gasification

In this study, thermodynamic equilibrium analysis of the sorption-enhanced chemical looping biomass gasification (SE-CL-BG) using Fe2O3 as the oxygen carrier, CaO as the CO2 sorbent, and CO2 or H2O as the gasifying agent for producing H2 rich syngas was conducted. Based on the amount of OC introduced, highly selective syngas can only result when a small amount of oxygen carrier is introduced. Due to carbon and hydrogen oxidations, the yields of CO and H2, cold gas efficiency, and the second-law efficiency of SE-CL-BG case were found to be lower than the conventional biomass gasification case in which no oxygen carrier and CO2 sorbent were introduced. Compared with conventional biomass gasification, the advantage of SE-CL-BG is that biomass gasification can be operated at lower temperatures (500–750 °C) with higher H2 yield due to the enhanced water-gas shift reaction and lower heat duty due to heat release from the CO2 absorption reaction. The computed results indicated that CaO loses the ability to absorb CO2 as the temperature becomes higher than 800 °C. •Sorption-enhanced chemical looping biomass gasification (SE-CL-BG) was studied.•Syngas selectivity decreases with increase in oxygen carrier amount introduced.•Higher H2 production can be obtained from SE-CL-BG with temperatures lower than 750 °C.•H2 production can be enhanced using more CO2 sorbent in SE-CL-BG.