Regeneration characteristics of Ca-poisoned commercial selective catalytic reduction denitrification catalyst
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摘要:
本研究分别选用络合剂氨基三甲叉膦酸(ATMP)、2-膦酸基丁烷-1,2,4-三羧酸(PBTCA)对钙中毒商用SCR脱硝催化剂(V2O5-WO3/TiO2)开展了再生方法研究,借助BET、NH3-TPD、H2-TPR和XPS等分析测试方法和实验探究考察了再生前后催化剂的理化特性及再生脱硝性能。结果表明,ATMP与PBTCA具有高效的再生性能,再生催化剂的脱硝效率在400 ℃下分别从25.8%恢复至89.8%与88.1%。与稀H2SO4再生相比,ATMP与PBTCA对催化剂的再生具有更高的除钙率与更低的钒损失率(不足5%)。使用ATMP与PBTCA对催化剂再生可有效恢复催化剂表面的Brønsted酸性位;催化剂表面的活性钒物种V5 + 和表面化学吸附氧Oα明显增加,催化剂整体活性达到最优水平。因此,将络合剂ATMP与PBTCA用于失活SCR脱硝催化剂的再生具有广阔的应用前景。
Abstract:Alkaline earth metal calcium is a typical poison in coal-fired power plants, which will result in deactivation of SCR catalyst. The ATMP (amino trimethylene phosphonic acid) and PBTCA (2-phosphonobutane-1,2,4-tricarboxylic acid) complexing agents were employed for the regeneration of a poisoned by calcium V2O5-WO3/TiO2 catalyst. The physical and chemical properties and regeneration denitration performance of the catalyst before and after regeneration were investigated by BET, NH3-TPD, H2-TPR, XPS and experiments. The results indicated that the ATMP and PBTCA exhibited efficient regeneration performance, and the NOx conversion of regenerating catalysts recovered from 25.8% to 89.8% and 88.1% at 400 ℃, respectively. Compared with the regeneration by dilute sulfuric acid, the ATMP and PBTCA exhibited a higher calcium removal rate with lower vanadium loss (less than 5%). The utilization of the ATMP and PBTCA can effectively restore the Brønsted acid sites, active vanadium V5 + and the surface chemisorbed oxygen Oα on the catalyst surface, which leads to the overall activity of the catalyst reaching an optimal level. Therefore, it has a great potential to apply ATMP and PBTCA complexing agents in the regeneration of deactivated SCR denitration catalysts.
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Key words:
- SCR catalysts /
- denitrification /
- Ca-poisoned /
- regeneration /
- complexing agent
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表 1 催化剂的元素组成
Table 1 Elemental component of catalysts(%)
Elemental Fresh Poisoned ATMP-S PBTCA-S H2SO4-S H2O-S Ca 0.99 3.38 1.03 1.08 1.38 1.75 V 0.34 0.33 0.33 0.33 0.30 0.32 W 4.31 4.15 4.13 4.12 3.98 4.12 表 2 催化剂的比表面积和孔体积
Table 2 Surface area and pore volume of catalyst
Catalyst BET surface area /
(m2·g−1)Pore volume /
(cm3·g−1)Pore diameter /
nmFresh 53.62 0.25 18.70 Poisoned 44.10 0.22 19.90 PBTCA-S 52.76 0.25 18.78 ATMP-S 53.03 0.24 18.84 表 3 催化剂的酸性位参数
Table 3 Acid sites parameters of catalysts
Catalyst Total acid amount /
(μmol·g−1)Brønsted acid
(1544 cm−1)Lewis acid
(1445 cm−1)Fresh 32.61 75.56 Poisoned 19.28 50.30 PBTCA-S 28.57 67.16 ATMP-S 30.32 71.45 -
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