SCR气氛下Ce-W/TiO2催化剂的脱硝协同脱汞特性

在固定床反应器上研究了反应温度和烟气组分对Ce-W/TiO₂（物质的量比Ce：W=2：1）催化剂脱硝协同脱汞活性的影响.结果表明：反应温度对该催化剂的脱硝脱汞效率影响显著，在280~400℃温度区间，脱硝效率随温度升高而升高，而脱汞效率在温度为280℃与360℃的条件下较高，360℃时兼具最好的脱硝与脱汞效率.在SCR气氛中，HCl对Hg⁰的氧化脱除有极大的促进作用，低浓度的HCl也有利于脱硝效率的提高，但HCl浓度过高对NO的脱除有抑制作用；SO₂的存在对脱硝过程可起到促进作用，对Hg⁰的氧化有抑制作用.利用BET，XRD，SEM，TPD，XRF，NH3-TPD等分析手段对反应前后催化剂进行表征，结果表明：Ce-W/TiO₂无微孔结构，活性组分CeO₂和WO₃以高度分散的形式分布于载体表面.280℃条件下部分Hg以HgCl₂的形式吸附于反应后催化剂表面，随着反应温度的升高催化剂表面吸附态的汞急剧降低.SCR气氛中的HCl与SO₂会影响催化剂表面酸性，同时增加Cl和S元素含量，进而影响该催化剂的脱硝与脱汞效率.

Characteristics of denitrification and mercury removal of Ce-W/TiO2 catalysts in SCR atmosphere

The effects of reaction temperature and flue gas composition on the denitrification and mercury removal efficiency of Ce-W/TiO₂ (Ce: W=2:1) catalysts were investigated in a fixed bed reactor. The results showed that the reaction temperature had a significant effect on the denitrification and mercury removal efficiency of Ce-W/TiO₂. In the temperature range of 280~400℃, the denitration efficiency increased as temperature increased, while the mercury removal efficiency was higher at temperature 280℃ and 360℃, with the best denitrification and mercury removal efficiency at 360℃. In the SCR atmosphere, HCl had a great effect on the oxidative removal of Hg⁰. Low concentration of HCl was also beneficial to the improvement of denitration efficiency, but excessive HCl concentration had an inhibitory effect on NO removal. The presence of SO₂ could promote the denitrification process and inhibit the oxidation of Hg⁰. The catalysts before and after the reaction were characterized by BET, XRD, SEM, TPD, XRF, NH3-TPD and other analytical methods. The results showed that Ce-W/TiO₂ had no microporous structure, and the active components CeO₂ and WO₃ were distributed on the surface of the carrier in a highly dispersed form. At 280℃, part of Hg was adsorbed on the surface of the catalyst in the form of HgCl₂. As the reaction temperature increased, the adsorption of mercury on the surface of the catalyst decreased sharply. HCl and SO₂ in SCR atmosphere could affect the acidity of catalyst surface and increase the content of Cl and S, thus, affect the denitration and mercury removal efficiency of the catalyst.