Ce-Mn/TiO2吸附剂的脱汞性能及抗SO2特性

采用浸渍法制备Mn/TiO₂（MT）、Ce/TiO₂（CT）和Ce-Mn/TiO₂（CMT）脱汞吸附剂，在固定床脱汞实验台上研究吸附剂的脱汞性能.结果表明，吸附温度为100~200℃时，3种吸附剂的脱汞性能均随温度的升高而增强；而在200~300℃范围内，脱汞效率均出现不同程度的降低.MT、CT及CMT吸附剂的脱汞效率在200℃时达到最高，分别为91%、58%和95%.MT和CT吸附剂的抗SO₂性能较弱，在N₂+6% O₂+1000×10^-6SO₂烟气条件下，30min内脱汞效率均下降到50%，而CMT吸附剂在2h内仍能保持80%以上的脱汞效率，表明在MT中掺杂Ce不仅可以提高吸附剂的脱汞性能，还可以增强抗SO₂性能.利用N₂吸附/脱附、X射线衍射（XRD）、H₂-程序升温还原（H₂-TPR）和X射线光电子能谱（XPS）等方法对吸附剂的物理化学性质进行表征，并对吸附产物进行热重分析（TG）和程序升温脱附实验（TPD），阐明了CMT脱汞吸附剂的抗SO₂特性机理.Ce的掺杂，提高了活性组分在吸附剂表面的分散度及Mn⁴⁺的比例；相比于MnO₂，CeO₂可优先与SO₂反应，抑制了SO₂对Mn⁴⁺的毒害作用，从而提高了抗硫性能.

Mercury removal performance and SO2 resistance of Ce-Mn/TiO2 sorbent

Mn/TiO₂ (MT), Ce/TiO₂ (CT) and Ce-Mn/TiO₂ (CMT) sorbents for mercury removal were prepared by the impregnation method. Mercury adsorption experiments were conducted on a fixed-bed reactor. The mercury removal performance of the three sorbents gradually increased with the increase of temperature in the range of 100~200℃. The maximum mercury capture efficiency of 91%, 58% and 95% were observed at 200℃ for MT, CT and CMT, respectively. The mercury removal efficiency decreased when the temperature was higher than 200℃. When MT and CT sorbents were exposed in the flue gas with N₂+6%O₂+1000×10^-6SO₂, the decrease of mercury removal efficiency to 50% within 30min was observed, indicating the weak SO₂resistance of MT and CT. However, mercury removal efficiency of more than 80% was maintained by CMT within 2h. It revealed that Ce doping in MT not only improved the mercury removal performance, but also enhanced the SO₂resistance. Physicochemical characteristics of the sorbents were analyzed by N₂adsorption/desorption, X-ray diffraction (XRD), H₂-temperature programmed reduction (H₂-TPR) and X-ray photoelectron spectroscopy (XPS). The spent sorbents were analyzed by thermogravimetric analysis (TG) and temperature programmed desorption (TPD) experiments. Based on the experimental and characterization results, the mechanism of SO₂resistance of the CMT for mercury removal was interpreted. The doping of Ce improved the dispersion of active components on the sorbent surface and the ratio of Mn⁴⁺, which was favorable for mercury removal; Compared with MnO₂, CeO₂preferentially react with SO₂, which inhibited the toxic effect on Mn⁴⁺, thus improving the SO₂resistance.