Abstract: With the rapid development of industry,the consumption of fossil fuels is increasing with each passing day,resulting in a large amount of greenhouse gas CO_2 emissions.The situation for global climate change is not optimistic.In order to reduce the emission of CO_2,it is necessary to capture,utilize and store the high concentration of CO_2.Oxy-fuel combustion technology can effectively achieve carbon capture,which is considered as one of the most potential carbon emission reduction technologies.In the process of oxy-fuel combustion,the existence of pollutants(including SO_x,NO_xand Hg) and inert gas is not conducive to carbon capture and storage.Since the concentration of various components in flue gas will affect pipeline transportation,geological storage,and enhanced oil recovery(EOR),the different standards of CO_2 and various impurities concentration in flue gas were introduced firstly,and the research progress of desulfurization,denitrification,mercury removal,inert gas removal,and combined removal technologies at home and abroad was systematically reviewed.In addition to the introduction of traditional desulfurization technology,the influence of CO_2 atmosphere in oxy-fuel combustion flue gas on SO_x removal and the conversion and removal of SO_2 under pressure were mainly described.It is found that the absorption rate of SO_2 in CO_2 atmosphere is lower than that in N_2 atmosphere,and the critical pH changes during the absorption process.In the denitration section,the denitration technology by oxidation absorption method and the oxidation mechanism of NO under high pressure were mainly described,and the oxidation kinetics of NO under high pressure was described.With the increase of pressure,the NO oxidation rate constant first decreases and then increases,which is proved that the effect of reactor pressure on liquid entrainment rate is significant.The effects of different flue gas components on Hg oxidation in Hg removal technology were summarized.HCl and Cl_2 play a significant role in promoting Hg oxidation.The activated carbon is modified to increase the specific surface area of pore structure and the active sites on the surface of adsorbent,so as to improve the removal efficiency of Hg.In this paper,the purification technology of inert gas was introduced.Pressure swing adsorption method is mainly used to adsorb and desorb,which reduces the cost of inert gas removal in CO_2 gas flow,realizes a part of inert gas recycling back to the boiler,and improves CO_2 capture.The combined removal technology in the flue gas compression liquefaction system is mainly discussed,which effectively uses the compression process conditions to remove SO_x,NO_x and Hg in the form of sulfuric acid,nitric acid and Hg(NO_3)_2.With the increase of pressure,the removal efficiency of SO_x and NO_x increases,which is conducive to the formation of SO_4~(2-),NO_3~-,HADS and HAMS(N-S compounds),and also leads to the increase of N_2O production.It is proved that the reaction of Hg with NO_2 is a gas phase reaction,and the uncertainty of the product of the reaction of NO_2 with Hg under high pressure is proposed.The low temperature carbon capture technology is briefly introduced,which has the potential to replace the scrubber and other flue gas treatment methods,but there is still a lack of feasibility research.In the future,it is necessary to explain the change trend of NO oxidation rate constant under different pressures,analyze the products of NO_x and SO_x combined removal and the reaction products of NO_2 and Hg under high pressure.