负载顺序对浸渍法制备Mn-Ce/TiO_(2)催化剂性能的影响

Effect of Loading Sequence on the Activity of Mn-Ce/TiO_(2) Catalysts Prepared by Impregnation

为了探究负载顺序对Mn-Ce/TiO催化剂氨选择性催化还原NO的影响,文章采用浸渍法制备了Mn-Ce/TiO低温SCR催化剂,并通过BET、SEM、XRD、FT-IR、H_(2)-TPR和NH_(3)-TPD对不同负载顺序的催化剂样品进行了表征,分析影响SCR活性的原因。结果表明,同时负载锰铈的催化剂脱硝活性最高,在反应温度为150 ℃的条件下,Mn-Ce/TiO催化剂的脱硝效率达到100%。BET和SEM结果表明,Mn、Ce同时负载催化剂的比表面积最大,且催化剂表面更加平整光滑,有利于催化活性;XRD结果表明,与同时负载锰铈的催化剂相比,锰铈分步负载时,其锰氧化物不够分散,都会影响催化剂中活性组分的晶体结构,从而影响催化剂性能。从H_(2)-TPR、NH_(3)-TPD分析可知,与锰铈同时负载比较,锰铈分步负载时,催化剂还原峰向高温方向发生了偏移,且催化剂表面酸性位点变弱,抑制了对NH的吸附能力,不利于NO的转化。

In order to investigate the effect of loading sequence on the performance of Mn-Ce/TiOlow temperature SCR catalyst, Mn-Ce/TiOcatalysts were prepared by impregnation method and used in selective catalytic reduction of NO with NHat low temperature. The catalysts were characterized by means of BET, SEM, XRD, FT-IR, H_(2)-TPR and NH_(3)-TPD. The influence of loading sequence on the structure of Mn-Ce/TiOcatalysts was investigated. The results showed that the catalyst activity was the highest when Mn and Ce were supported at the same time. The NO removal efficiency reached 100%, when the reaction temperature was 150 ℃. The results of BET and SEM showed that the specific surface area of the catalysts with Mn, Ce simultaneous supported was the largest, and the surface of the catalyst was smoother, which is conducive to catalytic activity. XRD results showed that when manganese and cerium were loaded step by step, the manganese oxide was not dispersed enough, which would affect the active components of the catalyst, thereby affecting the performance of the catalyst.From the analysis of H_(2)-TPR and NH_(3)-TPD, it was known that when the manganese cerium was loaded stepwise, the reduction peak of the catalyst shifted toward the high temperature, and the acid sites on the catalyst surface became weak, which inhibits the adsorption capacity of NH.