NOVELTY - The carbon dioxide (CO2) treatment system comprises a gasifier injector (26), a mixing chamber, a monitoring system (62), a control system (48), a carbon capture system (36), and an alarm system (82). The system includes a catalyst to treat CO2 to produce a treated CO2. The catalyst comprises a catalytic oxidizer, and is configured to remove hydrogen sulfide, hydrogen, carbon monoxide and/or methane from the CO2 to produce the treated CO2. The gasifier injector is configured to inject/receive the treated CO2, a fuel and oxygen into a gasifier (12) to gasify the fuel to produce a syngas.    USE - The system is useful for treating carbon dioxide, which is useful for refineries, petrochemical plants or power station, and is useful in an integrated gasification combined cycle system.    ADVANTAGE - The system is capable of economically, simply and reliably treating the carbon dioxide at high flow rate without any impurities thus producing the treated carbon dioxide with high quality.    DETAILED DESCRIPTION - The carbon dioxide (CO2) treatment system comprises a gasifier injector (26), a mixing chamber, a monitoring system (62), a control system (48), a carbon capture system (36), and an alarm system (82). The system includes a catalyst to treat CO2 to produce a treated CO2. The catalyst comprises a catalytic oxidizer, and is configured to remove hydrogen sulfide, hydrogen, carbon monoxide and/or methane from the CO2 to produce the treated CO2. The gasifier injector is configured to inject/receive the treated CO2, a fuel and oxygen into a gasifier (12) to gasify the fuel to produce a syngas, and comprises a common injection passage configured to flow both the treated CO2 and the oxygen as a single flow. The mixing chamber is configured to combine the treated CO2 and the oxygen. The monitoring system is configured to monitor a composition of the treated CO2. The control system is configured: to execute a corrective control function, if a hydrogen sulfide, hydrogen, carbon monoxide and/or methane in the composition of the treated CO2 is not within a threshold; to execute the corrective control function to reduce a flow of the treated CO2 through the gasifier injector, and to actuate a second CO2 catalytic treatment unit if a first CO2 catalytic treatment unit fails to maintain the substance in the composition of the catalytically treated CO2 within the threshold. The carbon capture system is configured to capture CO2 from the syngas. The alarm system is configured to output an alarm, if a substance in the composition of the treated CO2 is not within a threshold.    DESCRIPTION OF DRAWING(S) - The figure shows a block diagram of a CO2 treatment system.    Gasifier (12)    Gasifier injector (26)    Carbon capture system (36)    Control system (48)    Monitor system (62)    Alarm system. (82)