Novel effect of SO2 on selective catalytic oxidation of slip ammonia from coal-fired flue gas over IrO2 modified Ce-Zr solid solution and the mechanism investigation
Novel effect of SO2 on selective catalytic oxidation of slip ammonia from coal-fired flue gas over IrO2 modified Ce-Zr solid solution and the mechanism investigation
复制标题
SO2对IrO2改性Ce-Zr固溶体选择性催化氧化燃煤烟气逃逸氨的新作用及机理研究
DOI：
10.1016/j.fuel.2015.10.116
复制
发表时间：
2016-02-15
期刊：
影响因子：
7.4
通讯作者：
Yan, Naiqiang
中科院分区：
文献类型：
--
作者：
Chen, Wanmiao;Qu, Zan;Yan, Naiqiang
选择性催化还原（SCR）脱除燃煤烟气中NOx过程中产生的逃逸氨会导致系统性能下降和气溶胶等环境问题。为了实现氨选择性催化氧化制N2-，制备了IrO 2改性Ce-Zr固溶体催化剂，并在不同条件下进行了性能测试。结果表明，IrO 2/Ce0.6Zr0.4O2（PVP）催化剂对逃逸氨具有良好的催化活性，氨的脱除率可达98%以上。有趣的是，SO2对NH3氧化的影响是双向的，SO2的存在会导致催化剂的轻微失活，但在SO2和NH3共存的情况下，氧化产物的N-2选择性可高达100%。通过多种方法对IrO 2/Ce 0. 6 Zr 0. 4 O2（PVP）催化剂上NH3-SCO过程的机理进行了研究，结果表明，在不同温度范围内，NH3的氧化既遵循ANH机理，也遵循iSCR（内SCR）机理.主要的反应途径是iSCR反应机理，即吸附的氨首先被活化并与氧原子反应生成-HNO中间体。然后，-HNO可以被O-2中的原子氧氧化形成NO物种。同时，生成/吸附的NO可与-NH 2相互作用生成N2-，副产物为N2 O，SO2的存在可有效抑制N2 O和NO的生成，并对SO2的作用机理进行了合理的评价和确定. (C)2015由Elsevier Ltd.出版
The slip ammonia from selective catalytic reduction (SCR) of NOx in coal-fired flue gas can cause degeneration of the utilities and environmental issues like aerosol. To achieve selective catalytic oxidation (SCO) of slip ammonia to N-2, novel IrO2 modified Ce-Zr solid solution catalysts were synthesized and tested under various conditions. It was found that IrO2/Ce0.6Zr0.4O2 (PVP) catalyst displayed outstanding catalytic activity for slip ammonia and the removal efficiency was higher than 98%. Interestingly, the effect of SO2 on NH3 oxidation was bifacial, which the presence of SO2 could result in slight deactivation of catalyst but also improve the N-2 selectivity of oxidized products to as high as 100% with coexistence of SO2 and NH3. The mechanism of NH3-SCO process over IrO2/Ce0.6Zr0.4O2 (PVP) was evaluated through various techniques, and the results demonstrated that NH3 oxidation could follow both ANH mechanism and internal SCR (iSCR) mechanism at different temperature regions. And the dominant pathway is the iSCR mechanism, in which adsorbed ammonia is firstly activated and reacts with oxygen atoms to form the -HNO intermediate. Then, the -HNO could be oxidized with atomic oxygen from O-2 to form NO species. Meanwhile, the formed/adsorbed NO could interact with -NH2 to N-2 with N2O as by-product, and the presence of SO2 can effectively inhibit the production of N2O and NO. Also, the mechanism of SO2 effects was also evaluated and determined reasonably. (C) 2015 Published by Elsevier Ltd.