锰铈改性对Pt/BaCO_(3)/Al_(2)O_(3)催化剂NO_(x)存储性能的影响  

NO Storage Capacity of Pt/BaCO_(3)/Al_(2)O_(3) Catalysts with Mn and Ce Modification

作　　者：任德志 王成雄[1,2] 郭律 王波 杨冬霞 赵云昆 Ren Dezhi;Wang Chengxiong;Guo Lv;Wang Bo;Yang Dongxia;Zhao Yunkun(State Key Laboratory of Advanced Technologies for Comprehensive Utilization of Platinum Metal,Kunming Institute of Precious Metals,Kunming 650106,China;State-Local Joint Engineering Laboratory of Precious Metal Catalytic Technology and Application,Kunming Sino-platinum Metals Catalysts Co.Ltd,Kunming 650106,China)

机构地区：[1]昆明贵金属研究所,稀贵金属综合利用新技术国家重点实验室,云南昆明650106 [2]昆明贵研催化剂有限责任公司,贵金属催化技术与应用国家地方联合工程实验室,云南昆明650106

出　　处：《稀有金属》2021年第8期961-971,共11页Chinese Journal of Rare Metals

基　　金：国家自然科学基金项目(21862010,51676017);云南省重大科技专项项目(2018ZE017);云南省科技人才与平台计划项目(2018IC091)资助。

摘　　要：稀燃NOx存储技术是有效降低机动车NOx排放的关键技术之一,如何提高Pt/BaCO_(3)/Al_(2)O_(3)催化剂的性能是稀燃NOx存储技术的关键。通过分步浸渍法制备含CeO_(2)-x,MnO_(2)-x的Pt/BaCO_(3)/Al_(2)O_(3)催化剂,并采用N2吸脱附、X射线衍射(XRD)、氢气程序升温还原(H_(2)-TPR)对催化剂结构进行表征;利用NOx吸脱附试验、傅里叶变换红外(FT-IR)光谱技术研究NOx存储能力和存储机理。结果表明:CeO_(2)-x分散于Al_(2)O_(3)表面而部分MnO_(2)-x进入到了Al_(2)O_(3)的孔道内部,MnO_(2)-x对改善催化剂还原性和增加活性表面氧物种数量的能力明显优于CeO_(2)-x,从而促进NO低温氧化生成NO_(2)并以更加稳定的硝酸盐形式存储,同时抑制NOx在高温下以离子型硝酸盐结构吸附而提高存储NOx的释放能力。MnO_(2)-x或CeO_(2)-x均能够提高NOx的存储性能,但MnO_(2)-x和CeO_(2)-x共改性并没有表现出明显的优势。With the implementation of China VI standard,the improvement of fuel economy performance and the requirement of CO_(2) emission limits had been an inevitable trend to develop lean-burn engines for environmental protection and energy considerations. NOx purification under lean-burn conditions had become a research focus in the field of automotive exhaust gas after treatment. A three-way catalyst(TWC)required to be operated under near stoichiometric conditions,while NOx storage reduction(NSR)and selective catalytic reduction(SCR)catalysts were available to NOxremoval during lean-burn operations. However,a NSR catalyst was very suitable to remove NOx for a vehicle equipped with lean-burn gasoline or light-duty diesel engines. At present,it was considerably important to improve the performance of Pt/BaCO_(3)/Al_(2) O_(3) catalysts in the lean burn NOx storage technology. Optimizing the compositions and structures played a significant role in improving the reactivity of the catalysts. Such non-stoichiometric oxides(e.g. CeO_(2)-x,MnO_(2)-x)could not only effectively stabilize the active species in the platinum-supported catalysts,but also exhibit a superior reducibility. In addition,the interaction between platinum and non-stoichiometric oxides could affect the activity and stability of platinum-supported catalytic materials. The modified Pt/BaCO_(3)/Al_(2) O_(3) catalysts were prepared by the separate impregnation method to investigate the influence of Mn and Ce modification on NOx storage capacity. The catalysts were characterized by N2 adsorption-desorption technique,X-ray diffraction(XRD)and H_(2) temperature-programmed reduction(H_(2)-TPR). NOx storage capacity of the catalysts and the possible storage mechanisms were also investigated by Fourier transform infrared(FT-IR)spectroscopy and NOx adsorption-desorption technique. The results showed that the actual platinum loading in the catalyst was about 1.14%,and BaO content was 12.7%-15.0%. CeO_(2) content in Pt/CeBaAl and Pt/CeMnBaAl catalyst samples were 16.6% an

关 键 词：非化学计量氧化物 NO_(x)存储 稀燃工况 汽车尾气净化催化剂 

分 类 号：TQ426[化学工程]