CeO2改性再生SCR催化剂的单质汞氧化特性

对国内某1000MW燃煤发电机组失活选择性催化还原（SCR）催化剂进行CeO₂改性再生。对再生前后样品进行N₂吸附-脱附、扫描电子显微镜（SEM）、X射线荧光光谱（XRF）、傅里叶变换红外光谱（FTIR）对比表征分析。在自制固定床反应系统上对CeO₂改性再生催化剂（CeReCat）进行Hg⁰氧化性能测试，同时研究了SO₂、H₂O、NO和NH₃对Hg⁰氧化性能的影响。结果表明，CeO₂改性再生方法可有效清洗失活SCR催化剂表面杂质，恢复催化剂表面活性位点和孔隙结构，可使Ce、V两种活性元素得到有效负载。CeO₂改性后的样品Hg⁰氧化性能显著提升，3.0 CeReCat具有最佳Hg⁰的氧化效率。此外，烟气中加入600μL/L SO₂后，3.0 CeReCat仍具有高达74.4%的Hg⁰氧化效率，抗SO₂性能较好。烟气中的NO可轻微促进Hg⁰的氧化。由于竞争吸附作用，烟气中的H₂O和NH₃会抑制Hg⁰的氧化。CeO₂改性再生催化剂置于SCR系统下层时，由于烟气NH₃浓度较低而具有较高Hg⁰氧化效率，具有良好的应用前景。

Oxidation of elemental mercury by CeO2 modified regenerated SCR catalyst

The deactivated SCR catalyst from a 1000MW coal-fired generating unit in China was regenerated with CeO₂ modification. The samples before and after regeneration were characterized by N₂ adsorption-desorption, scanning electron microscope (SEM), X-ray fluorescence spectrum (XRF) and Fourier transform infrared spectrum (FTIR). Hg⁰ oxidation performance of the CeO₂ modified regenerated catalysts (CeReCat) were tested on a self-made fixed-bed reaction system, and the effects of SO₂, H₂O, NO and NH₃ on the Hg⁰ oxidation performance were studied. The results showed that the regeneration by CeO₂ modification could effectively remove the impurities on the surface of the deactivated SCR catalyst, restore the surface active sites and pore structure, and simultaneously effectively load Ce and V. The Hg⁰ oxidation performance of the CeO₂ modified samples was significantly improved, and 3.0 CeReCat had the best oxidation efficiency. In addition, when 600μL/L SO₂ was added to the flue gas, 3.0 CeReCat still had a high Hg⁰ oxidation efficiency of 74.4%, indicating a high SO₂ tolerance. NO in flue gas slightly promoted the oxidation of Hg⁰. Due to competitive adsorption, H₂O and NH₃ in flue gas inhibited the oxidation of Hg⁰. The CeO₂ modified regeneration catalyst exhibited a good application prospect when placed in the lower layer of SCR system where a low NH₃ concentration appeared.