Fe-loaded activated carbon for efficient flue gas deoxygenation and utilization in clean coal-fired power plants

Utilizing power plant flue gas to displace the atmosphere in coal mine goafs can achieve the dual goal of flue gas emission reduction and disaster prevention in coal mines. However, a large volume of the flue gas requires pre-treatment via deoxygenation. In this study, activated carbon was modified with Fe(NO3)3 to enhance its deoxygenation performance in a simulated flue gas atmosphere. The deoxygenation mechanism and catalytic oxidation kinetics of the Fe-loaded were comprehensively investigated using STA, fixed-bed chromatography, non-isothermal kinetic theory, quasi-in situ FTIR, XRD, and DFT. The results demonstrate that Fe-loading significantly enhances the deoxygenation performance of activated carbon in simulated flue gas. Both the ignition temperature and the temperature at maximum weight loss rate exhibited a linear decrease with increasing Fe loading, with maximum reductions of 26 °C and 22 °C, respectively. The Fe-loaded activated carbon exhibited a noble-metal-like performance by suppressing nearly 80% of CO emissions and maintaining excellent catalytic tolerance toward SO2 and NO2 poisoning. Kinetic analysis confirmed that Fe-loading reduced the activation energy in the initial combustion stage by 20 kJ/mol and caused the reaction model curve Z(α) to shift toward higher conversion ranges. Characterization and quantum chemical calculations further elucidated that Fe-loading significantly increased the concentration of surface oxygen-containing functional groups during the deoxygenation process in a flue gas atmosphere, with a maximum enhancement of 80%. Concurrently, the adsorption of Fe atoms drastically reduced the chemical hardness of the activated carbon by 5.03 eV and expanded the Fukui function regions, thereby providing a greater number of active sites for radical reactions. This work provides support for clean coal-fired power generation and lays a foundation for the directional catalytic conversion of carbonaceous materials.