铜物种分散性对Cu/AC脱硫剂低温反应性的影响

EFFECT OF CuO DISPERSION ON THE REACTIVITY OF Cu/AC DESULFURIZERS

新型Ｃｕ／ＡＣ脱硫剂在工业锅炉烟气排烟温度（１２０℃～２５０℃）下具有良好的脱硫活性．对不同载铜量的Ｃｕ／ＡＣ在２００℃下的脱硫活性进行了评价，并利用ＴＰＤ，ＴＰＯ，ＸＲＤ和ＥＸＡＦＳ等技术，分别对Ｃｕ／ＡＣ脱硫剂进行了表征，以考查铜物种分散性对其低温反应性的影响．研究结果表明， Ｃｕ／ＡＣ适宜的载铜量为 ５％～１５％，此时 Ｃｕ／ＡＣ兼具高的脱硫活性与铜利用率．尽管不同载铜量的 Ｃｕ／ＡＣ脱硫活性差异较大，但吸硫后均生成表面硫酸铜物种． Ｃｕ／ＡＣ在 ２００℃下用于烟气脱硫，只有高分散的表面ＣｕＯ物种可与ＳＯ２发生反应，体相ＣｕＯ与ＳＯ２不发生反应．经浓硝酸处理后的ＡＣ，表面含氧官能团浓度增加，大大改善了铜物种在ＡＣ表面的分散性．在５％的Ｃｕ／ＡＣ脱硫剂中，仅存在表面ＣｕＯ物种，当载钢量增至７％，体相ＣｕＯ开始出现，铜利用率降低．

Novel Cu/AC desulfurizers show high activity for SO2 removal at temperatures of flue gas derived from industrial boils. The activities of the Cu/AC desulfurizers with various Cu loadings at 200 ℃ were evaluated. In order to understand the relation of dispersion of CuO species over AC support and reactivity with SO2 at low temperatures, the Cu/AC desulfurizers were characterized by TPD, TPO, XRD and EXAFS techniques. It was found that the Cu/AC desulfurizers with the Cu loadings of 5 %-15 % shown high desulfurization activity and high utility efficiency for CuO, and Cu/AC reacted with SO2 from flue gas into surface CuSO4 species. When Cu/AC desulfurizers are used for desulfurization, only surface CuO species in Cu/AC desulfurizers can react with SO2 at 200 , body CuO can not react with SO2. Owing to the concentration of surface oxygen-containing functional groups on AC support after pretreated by HNO3 at 60 ℃ increases, the dispersion of CuO species on AC is improved. In the Cu/AC desulfurizers with the loadings of 5% and lower than 5%, only surface CuO species exists. As the Cu loading increases to 7%, body CuO begins to appear.