钾盐沉积对Mn-Ce/TiO_2低温SCR催化剂脱硝性能的影响

The poisoning effect of K depositing over Mn-Ce/TiO_2 catalyst for low-temperature selective catalytic reduction of NO by NH_3

采用浸渍法分别制备K_2CO_3、K_2SO_4、KNO_3和KCl四种钾盐前驱体沉积的Mn-Ce/Ti O_2催化剂,通过分析催化剂活性与催化剂理化特性之间的关系,考察碱金属钾沉积对Mn-Ce/Ti O_2低温SCR催化剂脱硝性能的影响。结果显示,钾的加入会导致催化剂中毒,且不同钾前驱体掺杂对催化剂中毒效应不同。KNO_3的沉积对Mn-Ce/Ti O_2催化剂脱硝效率的影响最小,而KCl沉积对催化剂活性抑制作用最为强烈。通过X射线晶体衍射(XRD)和程序升温脱附(TPD)的方法对不同催化剂进行表征发现,催化剂的晶型变化、表面活性元素及酸性点位的减少是催化剂中毒的主要原因。

Potassium carbonate （ K2CO3 ）, Potassium sulfate （ K2SO4 ）, Potassium nitrate（ KNO3 ）, and Potassi- um chloride （KCI） were chosen as the precursors to prepare the K salts deposited Mn - Ce/TiO2 catalysts through an impregnation method. The influence of K on the performance of the Mn - Ce/TiO2 catalyst for low - temperature selective catalytic reduction of NO by NH3 was investigated. Experimental results showed that K salts had negative effects on the activity of Mn - Ce/TiO2 and the precursors of Ksalts also affected the catalytic activity. The precursor KCI had a greater impact on the catalytic activity, while KNO3 had minimal effect. The samples were characterized by X -ray diffraction （XRD）, and NH3 temperature programmed desorption （ NH~ -TPD）. The characterization results indicated that the significant changes in physical and chemical properties of Mn - Ce/TiO2 were observed after K was deposited on the catalysts. The significant decreases in surface areas and NH3 adsorption amounts were observed after K was deposited on the catalysts, which could be considered as the main reasons for the deactivation of Ca deposited Mn - Ce/TiO2.