| 热处理天然褐铁矿制备γ-Fe2O3及其NH3-SCR活性探究 |
| 摘要点击 2990 全文点击 1293 投稿时间：2015-10-19 修订日期：2016-01-22 |
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| 中文关键词 褐铁矿 热处理 γ-Fe2O3 NH3-SCR H2O SO2 |
| 英文关键词 limonite thermaltreatment γ-Fe2O3 NH3-SCR H2O SO2 |
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| 中文摘要 |
| 以天然褐铁矿为前驱体,通过热处理制备γ-Fe2O3作为NH3-SCR催化剂.借助XRD、XRF、XPS、NH3-TPD、FR-IR等表征方法,考察反应温度、褐铁矿中的锰氧化物以及H2O和SO2对催化剂选择催化还原NO活性的影响并与α-Fe2O3作对比.结果表明,由于γ-Fe2O3表面比α-Fe2O3具有更强的酸性,使得γ-Fe2O3的脱硝温度窗口(200~350℃)宽于α-Fe2O3(200~300℃),且在活性温度窗口下,催化剂脱硝效率达到99%以上; γ-Fe2O3催化剂中少量MnO2的存在,提高了催化剂低温段(100~200℃)脱硝活性,降低了高温段(400~450℃)脱硝活性; SO2的存在会使γ-Fe2O3的脱硝温度窗口向高温区偏移100℃、体积分数为5%的H2O对脱硝反应的抑制作用很小,但当SO2和5%H2O同时存在,尤其是SO2的体积分数达到0.12%时,硫酸铵盐类的迅速生成会大大降低γ-Fe2O3的脱硝活性;此外,γ-Fe2O3经过NH3-SCR反应后,其磁化率略有降低,催化剂仍然具有磁回收循环利用的潜力. |
| 英文摘要 |
| Natural limonite was used as a precursor to prepare γ-Fe2O3 via thermal treatment. The influences of reaction temperature, manganese oxides existing in limonite and coexisting SO2 and H2O on the catalytic reduction activity of the preparedγ-Fe2O3 were evaluated, and the activity of SCR was compared with that of α-Fe2O3, by means of XRD, XRF, XPS, NH3-TPD, FT-IR and so on. The results showed that because the surface acidity of γ-Fe2O3 is stronger, the SCR temperature window of γ-Fe2O3 was 200-350℃ being broader than that of α-Fe2O3 (200-300℃), and in the active temperature window, the NO removal reached over 99%. The existence of MnO2 in the newly formed γ-Fe2O3 slightly decreased the SCR reactivity at lower temperature (100-200℃), while it decreased the SCR reactivity at higher temperature (400-450℃). The existence of SO2 led to the shifting of temperature window by 100℃ from 200-350℃ to 300-450℃, and the volume fraction of 5%H2O only had a tiny negative effect on the SCR reactivity of γ-Fe2O3. However, the coexisting SO2 and H2O, especially when the volume fraction of SO2 reached 0.12%, significantly decreased the SCR reactivity due to the generation of ammonium sulfate. Besides, although the magnetic susceptibility of reacted γ-Fe2O3 experienced a slight decrease compared with the newly prepared γ-Fe2O3, the catalysts could still be used repeatedly by magnetic recycling. |
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