Combined effects Na and SO2 in flue gas on Mn-Ce/TiO2 catalyst for low temperature selective catalytic reduction of NO by NH3 simulated by Na2SO4 doping
Combined effects Na and SO2 in flue gas on Mn-Ce/TiO2 catalyst for low temperature selective catalytic reduction of NO by NH3 simulated by Na2SO4 doping
复制标题
Na2SO4掺杂模拟NH3低温选择性催化还原烟气中Na和SO2对Mn-Ce/TiO2催化剂的联合作用
DOI：
10.1016/j.apsusc.2016.03.206
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发表时间：
2016
影响因子：
6.7
通讯作者：
Sheng Zhongyi
中科院分区：
文献类型：
--
作者：
Zhou Aiyi;Yu Danqing;Yang Liu;Sheng Zhongyi
采用浸渍法制备了一系列Mn-Ce/TiO 2催化剂，并将其用于氨低温选择性催化还原（SCR）NOx。在催化剂中加入Na 2SO 4模拟烟气中碱金属和SO2的联合作用。实验结果表明，Na 2SO 4对Mn-Ce/TiO 2催化剂活性的影响是强烈的、波动性的，因为Na 2SO 4的作用同时具有孔封闭和硫酸化作用。当Na 2SO 4负载量从0增加到1 wt.%时，Na_2SO_4掺杂后催化剂的SCR活性大大降低。随着Na_2SO_4用量的增加，催化活性逐渐提高。XRD结果表明，Na 2SO 4掺杂可以诱导MnOx晶化，TEM和SEM结果也证实了这一点。BET结果表明，随着Na 2SO 4用量的增加，催化剂的比表面积逐渐减小，并逐渐形成新的双峰介孔结构。XPS结果表明，Na 2SO 4沉积在催化剂表面后，部分Ce 4+和Mn 3+发生了硫酸化反应，转化为Ce 3+和Mn 4+。NH3-TPD结果表明，随着Na 2SO 4掺杂量的增加，Mn-Ce/TiO 2催化剂的刘易斯酸中心减少，而Brønsted酸中心迅速增加，这可能是催化剂活性变化的另一个原因。Mn和Ce原子浓度的降低、氧化态的改变以及Na 2SO 4掺杂后催化剂表面酸性的变化可能是导致催化剂活性波动变化的原因。
A series of Mn-Ce/TiO2catalysts were synthesized through an impregnation method and used for low temperature selective catalytic reduction (SCR) of NOx with ammonia (NH3). Na2SO4was added into the catalyst to simulate the combined effects of alkali metal and SO2in the flue gas. Experimental results showed that Na2SO4had strong and fluctuant influence on the activity of Mn-Ce/TiO2, because the effect of Na2SO4included pore occlusion and sulfation effect simultaneously. When Na2SO4loading content increased from 0 to 1 wt.%, the SCR activities of Na2SO4-doped catalysts decreased greatly. With further increasing amount of Na2SO4, however, the catalytic activity increased gradually. XRD results showed that Na2SO4doping could induce the crystallization of MnOx phases, which were also confirmed by TEM and SEM results. BET results showed that the surface areas decreased and a new bimodal mesoporous structure formed gradually with the increasing amount of Na2SO4. XPS results indicated that part of Ce4+and Mn3+were transferred to Ce3+and Mn4+due to the sulfation after Na2SO4deposition on the surface of the catalysts. When the doped amounts of Na2SO4increased, NH3-TPD results showed that the Lewis acid sites decreased and the Brønsted acid sites of Mn-Ce/TiO2increased quickly, which could be considered as another reason for the observed changes in the catalytic activity. The decreased Mn and Ce atomic concentration, the changes of their oxidative states, and the variation in acidic properties on the surface of Na2SO4-doped catalysts could be the reasons for the fluctuant changes of the catalytic activity.