Removal of pollution from the chemical looping process: A mini review

• Published in: Fuel processing technology Vol. 221; p. 106937
• Main Authors: Jiang, Hongming, Huo, Ruiqiang, Zhang, Zhen, Lin, Yan, Zhao, Zengli, Huang, Zhen, Fang, Yitian, Li, Haibin
• Format: Journal Article
• Language: English
• Published: Amsterdam Elsevier B.V 01.10.2021; Elsevier Science Ltd
• Subjects: Additives; Catalytic converters; Catalytic cracking; Catalytic oxidation; Chemical looping; Chlorine; Dechlorination; Denitration; Desulfurization; Energy utilization; Iron; Metal compounds; Metal oxides; Oxidation; Pollutants; Solid wastes; Tar removal; Tar removal; Desulfurization; Dechlorination; Chemical looping; Denitration
• ISSN: 0378-3820; 1873-7188
• DOI: 10.1016/j.fuproc.2021.106937

The chemical looping process (CLP), a technology that is completely different from the traditional heat utilization of fuel, has gained widespread attention not only for zero-CO2 emissions and cascade energy utilization but also in the field of pollution removal. Due to the low reaction temperature and N2-free reaction atmosphere, the property of low NOx emission was found in the early days of the technology's development. In CLP, oxygen carriers (OCs) can also remove tar through catalytic cracking, remove pollutants containing S/Cl by reacting with S/Cl to form metal compounds, and promote the conversion of Hg0 to Hg2+ through catalytic oxidation to promote subsequent removal of Hg. Recent advances in the removal of tar- and nitrogen-, sulfur-, chlorine- and mercury-containing pollutants in CLP are reviewed in this paper. On the basis of these findings, the effects of various oxygen carriers, additives and reaction conditions on the removal of various pollutants are discussed. Due to its environmental friendliness and low price, Fe-based OCs, especially Fe-rich natural ores and solid wastes, are the most promising for practical application. It is hoped that the synergistic removal of pollution can be achieved by loading a Cl/S absorbent and active metal oxides on OCs. •The low temperature and oxidation of OCs contribute to the low NOx emission in CLP.•OCs can reduce tar production through catalytic cracking and oxidation.•S and Cl can be removed by being fixed in OCs and ashes in CLP.•Oxidizing Hg0 to Hg2+ in the presence of OCs reduces the difficulty of subsequent Hg removal.•The coke leaking into the AR is the main source of NOx, SO2 and Hg emission in the AR.