Regeneration of Commercial SCR Catalysts: Probing the Existing Forms of Arsenic Oxide
Regeneration of Commercial SCR Catalysts: Probing the Existing Forms of Arsenic Oxide
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DOI：
10.1021/acs.est.5b02257
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发表时间：
2015-08-18
影响因子：
11.4
通讯作者：
Hao, Jiming
中科院分区：
文献类型：
--
作者：
Li, Xiang;Li, Junhua;Hao, Jiming
为了研究SCR催化剂的中毒和再生，对新鲜和砷中毒的工业V2 O 5-WO 3/TiO 2催化剂的失活机理和再生技术进行了研究。结果表明，中毒催化剂上砷氧化物的形态与催化剂上砷的含量有关。当（V+W+As）的表面覆盖度小于1时，三价砷物种（As-III）是主要组分，并且该物种倾向于渗透到体相通道中。然而，在高As浓度下，五价砷物种（As-IV）覆盖催化剂的表面。虽然这两种砷物种降低NOx转化率，但它们对N2 O形成的影响不同。特别地，当三价砷物种占优势时，N2 O的产生受到限制，这可能与As 2 O3堵塞催化剂的孔有关。相反，五价砷氧化物物种（As 2 O 5）具有几个As OH基团。这些As-OH基团不仅可以增强催化剂的还原能力，而且还提供了几个具有弱热稳定性的布朗斯台德酸中心，促进N2 O的形成。最后，虽然我们的新型Ca（NO3）（2）基再生方法不能完全从催化剂的微孔中去除As 2 O3，但这种方法可以有效地去除表面砷氧化物，而不会显著损失催化剂的活性组分。
To investigate the poisoning and regeneration of SCR catalysts, fresh and arsenic-poisoned commercial V2O5-WO3/TiO2 catalysts are researched in the context of deactivation mechanisms and regeneration technology. The results indicate that the forms of arsenic oxide on the poisoned catalyst are related to the proportion of arsenic (As) on the catalyst. When the surface coverage of (V+W+As) is lower than 1, the trivalent arsenic species (As-III) is the major component, and this species prefers to permeate into the bulkphase channels. However, at high As concentrations, pentavalent arsenic species (As-IV) cover the surface of the catalyst. Although both arsenic species lower the NOx conversion, they affect the formation of N2O differently. In particular, N2O production is limited when trivalent arsenic species predominate, which may be related to As2O3 clogging the pores of the catalyst. In contrast, the pentavalent arsenic oxide species (As2O5) possess several As OH groups. These As-OH groups could not only enhance the ability of the catalyst to become reduced, but also provide several Bronsted acid sites with weak thermal stability that promote the formation of N2O. Finally, although our novel Ca(NO3)(2)-based regeneration method cannot completely remove As2O3 from the micropores of the catalyst, this approach can effectively wipe off surface arsenic oxides without a significant loss of the catalyst's active components.