碳材料脱硫脱硝是控制钢铁烧结烟气SO2和NOx排放最有效的方法之一。目前国内外在新型碳材料制备和工艺开发等方面取得了重要进展，然而碳材料脱硫脱硝反应机理研究尤其是反应活性位的识别则相对滞后。虽然已有相关工作采用定性的研究方法探索碳材料脱硫脱硝的活性来源并取得了一些结果，但是由于碳材料表面结构的复杂性和不确定性，迄今为止科学界对参与脱硫脱硝反应的具体化学结构尚不明确，能够确定活性位的可靠实验证据也未见报道。因此，本论文围绕碳材料脱硫脱硝反应活性位识别开展了系统的研究工作，取得创新成果如下：（1）利用原位和非原位选择性钝化官能团策略，首次通过直接实验证据证明酮羰基是碳材料表面催化脱硝的主要活性位，并进一步调控酮羰基数量定量地建立了碳材料催化脱硝的“构效关系”。原位光谱实验和密度泛函理论模拟发现碳材料脱硝主要依靠表面酮羰基与酚羟基（C＝O/C?OH）之间的氧化还原循环完成，而NH3分子活化是反应的速率决定步骤。（2）利用程序升温脱附研究了碳材料表面非催化活性基团对脱硝的影响。结果表明碳材料表面羧基（?COOH）虽然对NH3具有较强的吸附能力，但是其吸附的NH3不参与脱硝反应。作为脱硝反应的非催化活性基团，羧基不仅在反应过程与活性位竞争吸附NH3，延长脱硝反应到达稳定状态所需时间，而且其吸附的NH3会在碳材料再生阶段释放，引发氨逃逸风险。（3）利用程序升温脱附定性地建立了碳材料脱硫活性与表面酮羰基的相关性，随后进一步采用选择性钝化实验证明酮羰基是碳材料烟气脱硫的主要活性位。在此基础上，通过瞬态实验、原位光谱和理论计算发现碳材料烟气脱硫过程按照Langmuir?Hinshelwood反应路径进行，其中酮羰基是化学吸附SO2的活性位，而其相邻sp2杂化碳原子解离活化O2分子产生活性氧物种，实现SO2氧化。（4）研究了碳材料表面结构在再生过程的演变机制及其对脱硫脱硝反应的影响。发现400 ℃再生会在碳材料表面残留SO42-物种，导致酮羰基吸附SO2受到抑制，从而降低了脱硫活性；500 ℃再生不但能够完全分解SO42-物种，而且会使碳材料表面C-S-C结构含量增加；C-S-C结构能够促进酮羰基对NH3的吸附和活化，从而提高了碳材料的脱硝活性，5次再生后脱硝率达到了初始碳材料脱硝率的4.2倍。

Cyclic desulfurization-regeneration-denitrification by carbon catalysts is one of the most effective technologies to simultaneously remove SO2 and NOx in sintering flue gas. Although significant progresses have been made on the synthesis of new catalysts and the development of application process, there is only limited growth of mechanistic interpretation of carbon-catalyzed flue gas desulfurization (FGD) and selective catalytic reduction (SCR)of NOx reactions. In particular, the nature of the catalytic active sites for FGD and SCR reactions over metal-free carbon catalysts still remains ambiguous owing to the surface complexity of the carbon, which has seriously hindered the rational design of efficient carbon catalysts. Thus, this work systematically identified the catalytic active sites for FGD and SCR reactions over metal-free carbon catalysts through experimental and theoretical studies. The main results are listed as following:(1) The ex-situ and in-situ selective passivation experiments directly evidenced that the nucleophilic ketonic carbonyl groups are the main intrinsic SCR active sites on metal-free carbon catalysts. The catalyst structure-activity relationship between the carbon catalyst and the SCR reaction was further quantitatively established by adjusting the amount of ketonic carbonyl groups. In addition, DFT calculations combined with in situ spectroscopy revealed that the standard carbon-catalyzed SCR reaction was depended on a redox cycle of ketonic carbonyl/phenol (C=O/C?OH) pairs, during which the activation of NH3 was the rate-limiting step.(2) The influence of catalytic inactive groups on the carbon catalyzed SCR reaction was studied by temperature-programmed desorption strategy. Although the electrophilic carboxyl groups (?COOH) on metal-free carbon catalysts exhibited strong adsorption toward NH3, they did not participate in the SCR reaction. As a result of the competitive adsorption of NH3 in the reaction step, these catalytic inactive carboxyl groups not only prolonged the time to the SCR steady state, but also resulted in the potential risk of NH3 slip. A linear relationship with the equimolar ratio between carboxyl groups and slipped NH3 was established in the regeneration steps. The slip of NH3 could be alleviated by the decomposition of carboxyl groups, and special attention should be paid to the presence of inactive sites with strong NH3 adsorption on industrial-employed SCR catalysts.(3) Temperature-programmed decomposition allowed us to modulate the number of oxygen functional groups on carbon catalysts and to establish its correlation with desulfurization activity. Selective passivation experiment further demonstrated that the ketonic carbonyl (C=O) groups are the intrinsic active sites for FGD reaction. Combined with transient response experiments, quasi-in situ X-ray photoelectron spectroscopy, and density functional theory simulations, it was revealed that desulfurization reaction on carbon catalysts mainly proceeded via the Langmuir?Hinshelwood mechanism, during which the nucleophilic ketonic C=O groups served as active sites for chemically absorbing SO2 and their adjacent sp2-hybridized carbon atoms dissociatively activated O2. It also turned out that the formation of H2SO4 is the reaction barrier step.(4) The transformation behaviors of the surface structure of carbon catalyst in the cyclic desulfurization-regeneration-denitrification process were systematically investigated. The SO42- species would remain on the surface when the activated carbon was regenerated at 400 ℃. The residual SO42- species decreased the desulfurization activity of the regenerated carbon due to their negative impacts on O2 activation. Nevertheless, the SO42- species would be completely decomposed once the regeneration temperature increased to 500 ℃. It is worth noting that regenerating at 500 ℃ resulted in the increase of C?S?C structure, which enhanced the SCR activity of regenerated AC owing to their promotional effect on the NH3 activation.