【作者】 陈家浩；

【导师】 王务林；

【作者基本信息】 天津大学 ， 环境化工， 2013， 博士

【摘要】 稀燃技术凭借其良好的高效节能性，赢得了人们的青睐，同时使得稀燃发动机技术得到了快速发展。应用于稀燃发动机尾气控制的技术便应运而生，其中主要包括NSR、SCR、DOC以及DPF等技术，而NO氧化步骤又是上述诸多控制技术中的关键环节，而钙钛矿型氧化物催化剂材料以其优异的催化性能、稳定的晶体结构以及低廉的价格，被认为是潜在的最具应用于机动车尾气净化处理技术前景的新型催化剂。本论文采用溶胶凝胶法，制备了镧基钙钛矿型氧化物LaMeO3（Me=Mn, Fe,Co）催化剂，用于NO氧化反应的研究，发现制备的样品均得到了单一晶相的钙钛矿结构。实验结果表明，LaCoO3的NO氧化性能最高，而LaFeO3的活性最差，LaMnO3的催化活性和结构稳定性均居中。钙钛矿表面吸附NO的能力以及催化剂自身的的氧化还原性能是控制NO氧化反应的关键因素。高温水热老化后，催化剂颗粒聚集长大，烧结现象明显，比表面积下降，催化活性也随之明显下降。考察了Co的掺杂改性对LaFeO3钙钛矿催化剂的NO氧化催化活性以及结构稳定性的影响。结果表明，Co的掺杂并未改变LaFeO3钙钛矿的晶体结构，同时提高了催化剂的NO氧化催化活性，且随着Co掺杂量的提高，催化剂的NO氧化活性逐渐增大。研究了非化学计量比La0.95Fe1-yCoyO3（y=0.1,0.2,0.3）钙钛矿的NO氧化催化性能，随着Co掺杂量的增大，催化剂的活性先增大后减小，La0.95Fe0.8Co0.2O3催化剂的NO氧化活性最高，非化学计量比使得低Co掺杂量的LaFeCoO3钙钛矿的表面出现Co离子富集现象，催化剂自身的氧化还原能力增强。水热老化后催化剂的颗粒聚集长大，烧结现象明显，比表面积下降。考察了非化学计量比对LaMnO3钙钛矿的NO氧化催化性能的影响，实验结果表明，非化学计量比明显提高了LaMnO3钙钛矿的催化活性，且随着La/Mn比例的增大，催化剂活性逐渐减小，B位产生更多的Mn4+离子，LaMnO3钙钛矿的催化活性与Mn4+及其与之配位的氧含量呈正相关性。由动力学实验测得LaxMnO3（x=0.9,0.95,1,1.05,1.11）系列钙钛矿的NO氧化反应活化能为44.8±2.7kJ/mol。水热老化后，催化剂出现烧结、颗粒长大现象，比表面积下降，催化活性降低。更多还原

【Abstract】 Lean combustion technology with high efficiency and energy saving have drawattention of many people. Lean burn engine exhaust aftertreatment technology hasbeen rapidly developed. Therefore, the new method applied to control the lean-burnengine exhaust is required, including NSR, SCR and DPF technology. NO oxidationis always play key role in those technologies. Perovskite materials with manyadvantages, such as the crystal structure, excellent stability and low cost advantage,are considered to be the potential catalysts applied to the motor vehicle exhaust aftertreatment.Lanthanum based perovskite-type catalyst LaMeO3(Me=Mn, Fe, Co) wasprepared by sol-gel method. The single crystal perovskite phase was obtained for allthe samples. The NO oxidation activity of LaCoO3is the highest, and the activity ofLaFeO3was the worst. The activity and structure stability of LaMnO3are middle ofthem. The surface adsorption ability and the reducibility of the catalyst is the keyfactor to control the NO oxidation reaction. At the same time, after hydrothermalaging, catalyst particle growed and the specific surface area decreased. The catalyticactivity decreased obviously, but LaCoO3perovskite still maintained a relatively highcatalytic performance.The effects of Co doping on the catalytic activity of LaFeO3perovskite andstructural stability were studied. The results show that, the doping of Co did notchange the crystal structure of LaFeO3, and improves the NO oxidation activity of thecatalyst. With the increased amount of Co doping, NO oxidation activity of thecatalyst increases. The doping of Co increased the content of active oxygen LaFeO3perovskite, also makes the catalyst surface adsorption ability enhancement NO.Study on the stoichiometric La0.95Fe1-yCoyO3(x=0.1,0.2,0.3) the catalyticperformance of perovskite. Experimental results show that, the nonstoichiometrysignificantly increases the NO oxidation activity of LaFeCoO3perovskite, especiallylow temperature activity. With the increase of the doping amount of Co, the activityof the catalyst increases first and then decreases, the La0.95Fe0.8Co0.2O3catalyst in NOoxidation activity was the highest, higher activity in250oC above2wt.%Pt/Al2O3catalyst. Non-stoichiometric makes LaFeCoO3perovskite surface low amount of Co doping Co ion concentration, enhance the oxidation catalyst surface reducing power,A La ion deficiency reduced stability of perovskite structure, while increasing theactivity of the catalyst. After hydrothermal aging catalyst particles were aggregatedsintering and specific surface area decreased.Finally, the catalytic properties of nonstoichiometric LaMnO3perovskite wereinvestigated. The experimental results show that, the non-stoichiometry significantlyimproved the catalytic activity of LaMnO3perovskite, and with the X value increases,catalyst activity decreases gradually. A La make LaMnO3Mn4+defect perovskite ionmore to maintain the price balance by B. More Mn4+ions content reduces thestructure stability of the catalyst, valence of Mn4+/Mn3+ion instability is the innerreason of catalyst with NO oxidation capacity. From the kinetic experiments ofLaxMnO3(x=0.9,0.95,1,1.05,1.11) perovskite for NO oxidation reaction, theactivation energy was44.8±2.7kJ/mol. After hydrothermal aging, the catalystsintering, grain growth phenomenon, the catalytic activity decreased.更多还原