SO₂ can noticeably impact the control of high toxic selenium emissions from flue gas by CaO. Surprisingly, our experiments showed that under certain conditions, SO₂ 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 SO₂ and solid Ca-S reaction products can promote SeO₂ converting to SeO/Se⁰. The Ca-S products facilitated greater SeO₂ conversion compared to SO₂. Experimental results demonstrated that selenium adsorption capacity of incompletely sulfurized CaO (CaO with pre-adsorbed SO₂) 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 SO₂ hardly affected selenium adsorption energy on the SO₂/CaO surface, while completely sulfurized CaO had low selenium adsorption energy, explaining the experimental phenomenon and proving necessary of CaO. Additionally, SeO/Se⁰ had higher adsorption energy on CaO than SeO₂. Overall, the promotion of SO₂ on selenium adsorption was primarily affected by two factors: 1) sulfur facilitating SeO₂ conversion to SeO/Se⁰ which can be adsorbed more easily by CaO; 2) sufficient adsorption sites on CaO surface existing for SeO/Se⁰ adsorption, despite co-adsorption with sulfur.

SO ₂可以显着影响CaO对烟气中高毒硒排放的控制。令人惊讶的是，我们的实验表明，在一定条件下，SO ₂可以促进而不是阻碍CaO对硒的捕获。为了阐明潜在的机制，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 ₂与固态Ca-S反应产物可以促进SeO ₂转化为SeO/Se ⁰。与 SO ₂相比， Ca-S 产品促进了更高的 SeO _2转化。实验结果表明，不完全硫化CaO（预吸附SO _2的CaO ）对硒的吸附能力高于完全硫化CaO（Ca-S产品），凸显了CaO吸附位点的重要性。密度泛函理论计算表明，预吸附的SO ₂对SO ₂ /CaO表面的硒吸附能几乎没有影响，而完全硫化的CaO具有较低的硒吸附能，解释了实验现象并证明了CaO的必要性。此外，SeO/Se ^{0对CaO的吸附能比SeO} ₂更高。_{总体而言，SO 2}的推广对硒吸附的影响主要受两个因素的影响：1）硫促进SeO ₂转化为更容易被CaO吸附的SeO/Se ^{0 。}2)尽管与硫共吸附，但CaO表面存在足够的吸附位点用于SeO/Se ^0吸附。