Abstract: Activated carbon flue gas purification technology can simultaneously remove various pollutants in flue gas with high removal efficiency, and has been widely applied to flue gas treatment in industries including iron and steel, non-ferrous metallurgy and coal-fired power generation. However, heat accumulation easily forms hot spots on activated carbon after adsorbing flue gas pollutants, bringing potential spontaneous combustion hazards. Therefore, systematic evaluation of the thermal stability of activated carbon under various adsorption conditions is of great engineering guiding significance. In this work, thermogravimetry-differential thermal analyzer (TG-DTA) was adopted to conduct thermal oxidation combustion experiments of activated carbon. The thermal stability characteristics of activated carbon under the coupling effects of single CO2, SO2, NOx atmospheres, multi-component mixed flue gas and different adsorption saturations were systematically investigated. Key kinetic parameters such as ignition temperature, burnout temperature, heat release characteristics and apparent combustion activation energy were quantitatively analyzed synchronously, and the coupling regulation mechanism between multi-pollutants and adsorption saturation was clarified. The results showed that CO2, SO2 and mixed atmospheres could raise the ignition temperature of activated carbon by 18~77℃, and reduce the average maximum heat release by 8% and 9% compared with raw activated carbon under CO2 and SO2 atmospheres, which remarkably suppressed spontaneous combustion risks. On the contrary, NOx atmosphere exerted an opposite effect, and the highest spontaneous combustion risk occurred at 100% adsorption saturation: the ignition temperature dropped to 340℃, the temperature corresponding to the maximum heat release rate decreased by 26℃ relative to raw carbon, and the average maximum heat release increased by 0.5 mW/mg. The kinetic barrier of carbon oxidation was greatly reduced, and the spontaneous combustion tendency was significantly intensified. The complex kinetic characteristics were governed by the mutual restriction of multiple effects, including competitive adsorption of CO2 on active sites, catalytic combustion promotion induced by chemically adsorbed NOx, and surface passivation and combustion inhibition from SO2 adsorption. This study identifies the distinctive spontaneous combustion risk of activated carbon with high adsorption saturation under NOx atmosphere, reveals the synergistic regulation law of coexisting multi-pollutants on the thermal oxidation properties of activated carbon, and provides theoretical support for the safe and stable operation of industrial activated carbon flue gas purification equipment.

Key words: activated carbon adsorption, multi-pollutants from flue gas, ignition temperature, maximum heat release rate

摘要： 活性炭法烟气净化技术可协同脱除烟气中多种污染物，净化效率高，已广泛应用于钢铁、有色、燃煤电厂等行业烟气治理，但活性炭吸附烟气污染物后易积热形成热点，存在自燃安全隐患，因此系统评估不同吸附工况下活性炭热稳定性具有工程指导意义。本研究采用热重-差热分析仪(TG-DTA)开展活性炭氧化燃烧试验，系统探究单一CO2, SO2, NOx气氛及多组分混合烟气、不同吸附饱和度耦合作用下活性炭的热稳定特性，同步定量分析着火温度、燃尽温度、放热特征与燃烧表观活化能等关键动力学参数，阐明多污染物与吸附饱和度的耦合调控机制。结果表明，CO2, SO2及混合气氛可将活性炭着火温度提升18~77℃，CO2及SO2气氛下平均最大放热量较原始炭分别降低8%和9%，显著抑制自燃风险；NOx气氛作用则相反，100%吸附饱和度时自燃风险最高，着火温度降至340℃，最大放热速率对应温度较原始炭下降26℃，平均最大放热量提升0.5 mW/mg，炭氧化动力学壁垒大幅降低，自燃倾向性显著增强。复杂动力学特征源于CO2位点竞争吸附、NOx化学吸附催化促燃、SO2表面钝化抑燃多重效应相互制衡。本研究明确了高吸附饱和NOx气氛下活性炭特殊自燃风险，揭示多污染物共存时对活性炭热氧化特性的协同调控规律，为工业烟气活性炭净化装置安全稳定运行提供理论支撑。

关键词: 活性炭吸附, 烟气多污染物, 着火温度, 最大放热速率