Abstract:

The deactivated denitration catalysts used in a coal-fired power plant were washed and then immersed in activation solutions with oxalic acid and ethanolamine respectively as cosolvents for investigating the regeneration effect. The fresh, deactivated, and two regenerated catalysts were analyzed with XRF, N₂-physisorption, in-situ pyridine adsorption, NH₃-TPD, Raman, XPS, H₂-TPR, and then were tested in a fixed bed denitration catalytic reactor. The major deactivation of denitration catalysts was because that the K, Na from fly ash caused loss of specific surface area, pore volume, Lewis acid sites, active VO _x species, and ratio of V⁵⁺, and weakened the catalysts’ oxidation-reduction ability. Meanwhile, the two regenerated catalysts with the same vanadium content showed great difference on the denitration efficiencies. Ethanol-cat, regenerated by ethanolamine-assisted activation solution had denitration efficiency over 97% of that of the fresh catalyst. However, Oxalic-cat, regenerated by oxalic acid-assisted activation solution showed almost no regeneration effect. This was due to the vanadium species with different states in the two activation solutions. The vanadium species in ethanolamine-assisted activation solution could recover Lewis acid sites, ratio of V⁵⁺ and active VO _x species of the deactivated catalysts, and enhance the oxidation-reduction ability of catalysts effectively, but the vanadium species in oxalic acid-assisted activation solution could hardly attain these results.

Key words: regeneration, activation solution, cosolvent, denitration catalyst, deactivation

摘要：

为了考察助溶剂对活化液的催化剂再生性能的影响，将某燃煤电厂失活退役的脱硝催化剂在相同清洗工艺下处理，随后分别浸入以草酸、乙醇胺作为助溶剂配制的活化液中，得到两个再生催化剂。采用XRF、氮气物理吸附法、原位吡啶吸附、NH₃-TPD、Raman、XPS、H₂-TPR以及固定床脱硝反应器等表征手段对新鲜样品、失活样品以及再生样品进行表面理化性质、脱硝性能测试评价。结果显示，脱硝催化剂失活的主要原因是飞灰中的碱金属K、Na造成催化剂的比表面积和孔容下降、表面Lewis酸性位数量减少、V⁵⁺比例下降、活性VO _x 减少及氧化还原性能下降。同时发现，两个再生催化剂在等量活性组分钒条件下，脱硝性能却表现出较大差异，乙醇胺助溶活化液再生的样品Ethanol-cat性能恢复至新鲜催化剂的97%以上，而草酸助溶活化液再生的样品Oxalic-cat却几乎无再生效果，这是因为两种活化液中的活性组分钒状态不同，乙醇胺助溶活化液中钒离子可有效恢复失活催化剂的酸性位数量、V⁵⁺比例、活性物种VO _x 数量以及氧化还原性能，而草酸助溶活化液对失活催化剂的这些理化性质作用较小。

关键词: 再生, 活化液, 助溶剂, 脱硝催化剂, 失活机理