摘要
采用Fe对MnOx催化剂的低温选择性催化还原(SCR)活性进行改性,并通过N2吸附、X射线衍射(XRD)、X射线光电子能谱(XPS)及原位漫反射傅里叶红外(insituDRIFTS)重点探讨了Fe引入后催化剂结构性质的变化及对低温SCR反应机制的影响.结果表明,Fe的掺杂能显著提高催化剂的低温SCR性能,Fe/(Fe+Mn)物质的量比为0.3,400℃下焙烧而成的Fe(0.3)-MnOx(400)催化剂具有最佳的低温活性及N2选择性.铁锰间存在较强的相互作用,Fe掺杂后催化剂部分氧化物呈无定形结构,锰在催化剂表面富集,催化剂的晶格氧量增加的同时其稳定性降低,具有优良的氧化还原性能.原位漫反射傅里叶红外光谱(insituDRIFTS)结果显示,Fe的添加增强了催化剂吸附NH3的活化脱氢能力,使得反应中NO的吸附态主要呈现为具有较高活性的亚硝酰基(NO-)构型,促进了吸附物种在催化剂颗粒表面产生快速、可逆的氧化/还原反应,从而显著提高了NOx的去除效率.
MnOx catalyst was modified with Fe substitution and the structure properties of composite oxide and reaction pathway of low temperature SCR was investigated by N2 adsorption,XRD,XPS and in situ DRIFTS.The activity was greatly enhanced after the substitution and the highest SCR activity and N2 selectivity was achieved on Fe-Mn mixed oxides with the molar ratio of Fe/（Fe ＋ Mn） = 0.3 calcined at 400 ℃.Amorphous structure was observed resulted from the interaction of Fe and Mn,with Mn enriched on the surface and enhanced mobile lattice oxygen,leading to better redox properties.The in situ DRIFTS results indicated that the addition of Fe contributed to the activation of adsorbed NH3 species and maintained the adsorption of NO in the high activity NO-form.Therefore,a fast and reversible redox process between the adsorbed species developed on the catalyst surface,resulting in remarkable enhancement of the NOx conversion.
出处
《环境科学学报》
CAS
CSCD
北大核心
2011年第10期2091-2101,共11页
Acta Scientiae Circumstantiae
基金
国家自然科学基金项目(No.20977034)
大气污染控制广东高校工程技术研究中心资助项目(No.N910009a)
广东高校科技成果转化项目(No.cgzhzd0803)~~
