Review and Outlook of Theoretical Understanding on Pollutants Reaction Mechanism during Chemical Looping Combustion

Chemical looping combustion (CLC) has emerged as a promising technology for CO2 capture with low cost and energy penalty. In the CLC system, pollutants containing sulfur, nitrogen, and mercury originating from solid fuels are inevitably generated, which will not only lead to equipment corrosion and environmental problems but also affect the purity of CO2 captured by CLC. The reaction mechanism of pollutants with oxygen carriers is closely associated with the pollutant removal efficiency of the CLC system. Density functional theory (DFT) calculations have been widely used to reveal the reaction mechanism of pollutants with oxygen carriers at the atomic level. Thus, this work reviews the research progress on the reaction mechanism of different pollutants with oxygen carriers through DFT calculations during chemical looping combustion. The effects of pollutants containing sulfur, nitrogen, and mercury on the reactivity of oxygen carriers are systematically elucidated, and the reaction pathways of pollutants on the oxygen carrier surface are discussed. Furthermore, the influence mechanism of various flue gas components on the interaction between pollutants and oxygen carriers is summarized. Finally, we provide an outlook on the reaction mechanism of pollutants with oxygen carriers during chemical looping combustion.