Hong Qinyuan, Xu Haomiao, Pang Xingyu, Liu Wei, Liu Zhisong, Huang Wenjun, Qu Zan, Yan Naiqiang
School of Environmental Science and Engineering, Shanghai Jiao Tong University, Shanghai 200240, China.
China-UK Low-Carbon College, Shanghai Jiao Tong University, Shanghai 200240, China.
Environ Sci Technol. 2022 Aug 2;56(15):10935-10944. doi: 10.1021/acs.est.2c02362. Epub 2022 Jul 22.
Sulfur trioxide (SO) is an unstable pollutant, and its removal from the gas phase of industrial flue gas remains a significant challenge. Herein, we propose a reverse conversion treatment (RCT) strategy to reduce S(VI) in SO to S(IV) by combining bench-scale experiments and theoretical studies. We first demonstrated that metastable sulfides can break the S-O bond in SO, leading to the re-formation of sulfur dioxide (SO). The RCT performance varied between mono- and binary-metal sulfides, and metastable CuS had a high SO conversion efficiency in the temperature range of 200-300 °C. Accordingly, the introduction of selenium (Se) lowered the electronegativity of the CuS host and enhanced its reducibility to SO. Among the CuSeS composites, CuSeS was the optimal RCT material and reached a SO yield of 6.25 mmol/g in 120 min. The low-valence state of selenium (Se/Se) exhibited a higher reduction activity for SO than did S/S; however, excessive Se doping degraded the SO conversion owing to the re-oxidation of SO by the generated SeO. The density functional theory calculations verified the stronger SO adsorption performance ( = -2.76 eV) and lower S-O bond breaking energy ( = 1.34 eV) over CuSeS compared to those over CuS and CuSe. Thus, CuSeS can serve as a model material and the RCT strategy can make use of field temperature conditions in nonferrous smelters for SO emission control.
三氧化硫（SO₃）是一种不稳定的污染物，从工业烟气的气相中去除它仍然是一项重大挑战。在此，我们通过结合实验室规模的实验和理论研究，提出了一种反向转化处理（RCT）策略，将SO₃中的S(VI)还原为S(IV)。我们首先证明了亚稳硫化物可以打破SO₃中的S - O键，导致二氧化硫（SO₂）的重新形成。RCT性能在单金属和双金属硫化物之间有所不同，亚稳CuS在200 - 300°C的温度范围内具有较高的SO₃转化效率。因此，硒（Se）的引入降低了CuS主体的电负性并增强了其对SO₃的还原性。在CuSeS复合材料中，Cu₂SeS是最佳的RCT材料，在120分钟内达到了6.25 mmol/g的SO₂产率。低价态的硒（Se⁰/Se²⁻）对SO₃的还原活性高于S⁰/S²⁻；然而，过量的Se掺杂由于生成的SeO₂对SO₂的再氧化而降低了SO₃的转化率。密度泛函理论计算验证了与CuS和CuSe相比，Cu₂SeS对SO₃具有更强的吸附性能（ΔG = -2.76 eV）和更低的S - O键断裂能（E = 1.34 eV）。因此，Cu₂SeS可以作为一种模型材料，并且RCT策略可以利用有色金属冶炼厂的现场温度条件来控制SO₂排放。
