Performance and kinetics study for low-temperature SCR of NO with NH3 over MnOx-CeO2 catalyst
Performance and kinetics study for low-temperature SCR of NO with NH3 over MnOx-CeO2 catalyst
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DOI：
10.1016/s0021-9517(03)00081-2
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发表时间：
2003-07-25
影响因子：
7.3
通讯作者：
Yang, RT
中科院分区：
文献类型：
--
作者：
Qi, GS;Yang, RT
采用不同方法制备了一系列锰铈氧化物催化剂，并将其用于过量O2存在下氨低温选择性催化还原（SCR）脱硝反应。Mn-Ce-O-x催化剂具有较高的活性。实验结果表明，Mn-Ce复合氧化物催化剂在120 ℃、42, 000 h（-1）高空速条件下，NO转化率接近100%。随着锰含量从0增加到30%（即，Mn/（Mn + Ce）摩尔比），NO转化率显著增加，但随着Mn含量的增加而降低。在Mn/（Mn + Ce）摩尔比为0.3的情况下获得最具活性的催化剂。研究了煅烧温度对产物的影响，最佳煅烧温度为650 ℃。这些催化剂比文献中报道的所有其他催化剂活性高得多。SO2和H2O（高浓度）对SCR活性影响不大。从稳态动力学研究中，人们发现，低温SCR反应是零级相对于NH3和一级相对于NO。与其他催化剂相比，低温SCR的NO与氨，根据一级速率常数，MnOx-CeO 2催化剂是几倍以上的活性比其他催化剂在文献中报道。当温度低于150 ℃时，产物中只有N-2而没有N2 O。在较高的温度下，检测到痕量的N2 O。(C)2003 Elsevier Science（美国）。All rights reserved.
A series of manganese-cerium oxide catalysts were prepared by different methods and used for low-temperature selective catalytic reduction (SCR) of NOx with ammonia in the presence of excess O-2. The Mn-Ce-O-x catalysts showed high activities. The experimental results showed that the best Mn-Ce mixed-oxide catalyst yielded nearly 100% NO conversion at 120 degreesC at a high space velocity of 42,000 h(-1). As the manganese content was increased from zero to 30% (i.e., the molar ratio of Mn/(Mn + Ce)), NO conversion increased significantly, but decreased at higher manganese contents. The most active catalyst was obtained with a molar Mn/(Mn + Ce) ratio of 0.3. The effect of the calcination temperature was also investigated and the optimum calcination temperature was 650 degreesC. These catalysts are substantially more active than all other catalysts reported in the literature. SO2 and H2O (at high concentrations) have slight effects on the SCR activity. From a steady-state kinetics study, it was found that the low-temperature SCR reaction was zero order with respect to NH3 and first order with respect to NO. Compared with the other catalysts reported for low-temperature SCR of NO with ammonia, based on the first-order rate constants, the MnOx-CeO2 catalyst was several times more active than other catalysts reported in the literature. Only N-2 rather than N2O was found in the product when the temperature was below 150 degreesC. At higher temperatures, trace amounts of N2O were detected. (C) 2003 Elsevier Science (USA). All rights reserved.