Mechanism of enhanced SO2 and NO adsorption of CaO by red mud doping
The rich iron oxide in red mud possesses catalytic properties,and blending a certain proportion of red mud can be used to modify Ca-based desulfurization and denitrification adsorbents.To explore the mechanism by which red mud doping enhances the desulfurization and denitrification performance of calcium-based adsorbents,red mud/CaO adsorbents with varying doping ratios were prepared using the extrusion molding method.Utilizing a fixed-bed reactor system to simulate actual flue gas conditions,adsorption performance and DFT sim-ulation studies were conducted.Based on density functional theory,CaO(001)surface models and Fe-CaO(001)surface models were constructed,and the impact of red mud doping on the adsorption performance of CaO for SO2 and NO was revealed through calcula-tions and analyses at the microscopic atomic level.The experimental results show that when the addition of red mud is 5％,the red mud/CaO adsorbent significantly extended the efficient adsorption time for SO2 and markedly improve the adsorption efficiency for NO,increas-ing from 62.5％to 84.0％,confirming the effectiveness of red mud doping in enhancing adsorbent performance.The simulation calculation results indicate that red mud doping reduced the adsorption energy of SO2 and NO from-1.181 eV to-2.247 eV and from-0.601 eV to-0.977 eV,respectively.Furthermore,after doping with red mud,the interactions between Fe atoms,O atoms,and S atoms(or N atoms)produces three atomic orbital resonance peaks with high state density,indicating that red mud doping enhances the stability of the CaO structure and intensifies the interactions between Fe and O atoms,thereby increasing the reactivity of O atoms.Consequently,red mud do-ping improves the chemical adsorption performance of CaO for SO2 and NO.
万方数据
