Key Laboratory of Energy Thermal Conversion and Control of Ministry of Education, School of Energy and Environment, Southeast University, Nanjing, Jiangsu 210096, PR China; Department of Transdisciplinary Science and Engineering, School of Environment and Society, Tokyo Institute of Technology, Kanagawa, Yokohama 2268503, Japan.
Department of Transdisciplinary Science and Engineering, School of Environment and Society, Tokyo Institute of Technology, Kanagawa, Yokohama 2268503, Japan.
J Hazard Mater. 2023 Sep 5;457:131742. doi: 10.1016/j.jhazmat.2023.131742. Epub 2023 May 30.
SO can noticeably impact the control of high toxic selenium emissions from flue gas by CaO. Surprisingly, our experiments showed that under certain conditions, SO can promote selenium capture by CaO, rather than hinder it. To elucidate the underlying mechanism, a combination of theoretical calculations and experiments was conducted. Thermodynamic equilibrium analysis revealed that gaseous SO and solid Ca-S reaction products can promote SeO converting to SeO/Se. The Ca-S products facilitated greater SeO conversion compared to SO. Experimental results demonstrated that selenium adsorption capacity of incompletely sulfurized CaO (CaO with pre-adsorbed SO) was higher than that of completely sulfurized CaO (Ca-S products), highlighting the importance of adsorption sites of CaO. Density functional theory calculations showed that the pre-adsorbed SO hardly affected selenium adsorption energy on the SO/CaO surface, while completely sulfurized CaO had low selenium adsorption energy, explaining the experimental phenomenon and proving necessary of CaO. Additionally, SeO/Se had higher adsorption energy on CaO than SeO. Overall, the promotion of SO on selenium adsorption was primarily affected by two factors: 1) sulfur facilitating SeO conversion to SeO/Se which can be adsorbed more easily by CaO; 2) sufficient adsorption sites on CaO surface existing for SeO/Se adsorption, despite co-adsorption with sulfur.
SO 可显著影响 CaO 对烟道气中高毒性硒排放的控制。令人惊讶的是，我们的实验表明，在某些条件下，SO 可以促进 CaO 对硒的捕获，而不是阻碍它。为了阐明其潜在机制，我们进行了理论计算和实验的结合。热力学平衡分析表明，气态 SO 和固体 Ca-S 反应产物可以促进 SeO 转化为 SeO/Se。与 SO 相比，Ca-S 产物更有利于 SeO 的转化。实验结果表明，不完全硫化的 CaO（预先吸附 SO 的 CaO）的硒吸附容量高于完全硫化的 CaO（Ca-S 产物），这突出了 CaO 吸附位的重要性。密度泛函理论计算表明，预先吸附的 SO 几乎不会影响 SO/CaO 表面上硒的吸附能，而完全硫化的 CaO 的硒吸附能较低，这解释了实验现象并证明了 CaO 的必要性。此外，SeO/Se 在 CaO 上的吸附能高于 SeO。总的来说，SO 对硒吸附的促进主要受两个因素的影响：1）硫促进 SeO 转化为更容易被 CaO 吸附的 SeO/Se；2）CaO 表面上存在足够的吸附位，尽管与硫共吸附，但仍可用于 SeO/Se 的吸附。
