非化学计量比对Sm_(x)Mn_(2)O_(5)莫来石催化氧化柴油机尾气炭烟性能的影响  

Influence of non-stoichiometry on diesel soot oxidationperformance of Sm_(x)Mn_(2)O_(5) mullites

作　　者：靳保芳 王延绅 李震国 马越 吴晓东 冉锐 翁端 JIN Baofang;WANG Yanshen;LI Zhenguo;MA Yue;WU Xiaodong;RAN Rui;WENG Duan(The Key Laboratory of Advanced Materials of Ministry of Education,School of Materials Science and Engineering,Tsinghua University,Beijing 100084,China;Institute of Process Engineering,Chinese Academy of Sciences,Beijing 100190,China;National Engineering Laboratory for Mobile Source Emission Control Technology,China Automotive Technology&Research Center,Tianjin 300300,China)

机构地区：[1]清华大学材料学院,先进材料教育部重点实验室,北京100084 [2]中国科学院过程工程研究所,北京100190 [3]中国汽车技术研究中心,移动源排放控制技术国家工程实验室,天津300300

出　　处：《陕西师范大学学报（自然科学版）》2022年第2期38-43,F0002,共7页Journal of Shaanxi Normal University：Natural Science Edition

基　　金：十三五重点研发计划(2017YFC0211102);国家自然科学基金(21906091);移动源污染排放控制技术国家工程实验室开放基金(NELMS2020A08,NELMS2017A13)。

摘　　要：采用溶胶-凝胶法合成了3种不同Sm含量的锰基莫来石复合氧化物(Sm_(0.8)Mn_(2)O_(5)、Sm_(x)Mn_(2)O_(5)和Sm_(1.2)Mn_(2)O_(5)),并对其进行炭烟催化氧化活性评价及XRD、BET、H_(2)-TPR、O_(2)-TPD、NO-TPO等表征。研究结果表明,Sm/Mn比值对合成催化剂的微观结构和炭烟催化氧化性能有重要影响。当Sm/Mn<0.5时,Sm_(0.8)Mn_(2)O_(5)展现出最佳炭烟催化氧化活性(T_(50)=378℃);此时,催化剂中Sm元素缺失,导致莫来石产生A位缺陷并生成表面MnO_(x)团簇,可以吸附更多的活性氧物种,进而促进NO和炭烟氧化。相反,当Sm/Mn>0.5时,Sm_(1.2)Mn_(2)O_(5)催化剂中A位元素过量,致使莫来石中形成了较多的钙钛矿杂相,降低了催化剂的氧化还原性能,不利于催化反应的进行。Three manganese based mullite-type mixed oxides(Sm_(0.8)Mn_(2)O_(5),Sm_(x)Mn_(2)O_(5)and Sm_(1.2)Mn_(2)O_(5))with different samarium contents were synthesized by a sol-gel method.The catalysts were evaluated for catalytic oxidation performance of soot and characterized by XRD,BET,H_(2)-TPR,O_(2)-TPD and NO-TPO.The results showed that Sm/Mn ratio played important roles in the microstructure and catalytic oxidation performance of the synthesized catalysts.In the case of Sm/Mn<0.5,Sm_(0.8)Mn_(2)O_(5)catalyst exhibited the highest catalytic activity with a T_(50)value of 378℃.Under the above circumstances,more A-site defects were produced in the mullite due to the insufficient Sm amount.This,together with the production of surface MnO_(x)clusters,generated more active oxygen species and promoted the oxidation of NO and soot.Contrarily,given a Sm/Mn ratio higher than 0.5,excessive Sm led to the formation of more SmMnO_(3) perovskite-type oxides and weakened the redox ability of the catalyst in oxidation reactions.

关 键 词：莫来石 非化学计量比 钙钛矿 炭烟氧化 

分 类 号：O643[理学—物理化学]