The crucial role of deoxygenation in syngas refinement and carbon dioxide utilization during chemical looping-based biomass gasification

Abstract

Reducing anthropogenic CO2 emissions has become a primary environmental concern for the present society, making the development of energy-efficient, net-negative CO2 emitting technology paramount. Here, the Chemical looping deoxygenated gasification (CLDG) process is experimentally conducted to demonstrate the crucial role of deoxygenation on syngas refinement and CO2 utilization via Fe0 ↔ Fe3+ looping. A reduction of 0.324 g CO2 per gram pine wood biomass gasified is achieved, a 288% reduction in CO2 emissions compared with that of biomass conversion without deoxygenation. The superiority of CLDG can be also reflected in syngas yields increased by 16.37% and a CO2 concentration decreased by 44.16%. Results from the heat balance calculation indicate that both the gasifier and the regenerator are endothermic, which cannot achieve the auto-thermal operation of CLDG, thus requires an extra energy supply source. Density functional theory calculations elucidate that the active site of CO2 adsorption is located at the three-phase interface of CaO(111), Fe(110), and amorphous carbon (AC). It is anticipated that CLDG has the potential to serve as an effective measure for reducing CO2 emissions while promoting syngas yield and quality.