双掺杂稀土钙钛矿型多孔纳米管稀燃NOx阱催化剂研究

Lean-burn combustion can improve the fuel efficiency and reduce the emission of CO2. However, the presence of excess oxygen increases the difficulty of NOx removal in exhaust. Lean-burn NOx trap (LNT) technique is one of the most effective ways to solve the problem. Our previous research has confirmed that rare-earth perovskites (ABO3) show as good LNT activities as noble-metal catalysts. The alkali metal dopant in A site can further improve its LNT activities due to the increases of oxygen vacancies. Meanwhile, Fe dopant in B site can improve its sulfur resistance. However, the small specific surface area and structure destruction occurred during lean/rich cycles limit the application of traditional perovskite-type catalysts. .To overcome these problems, this project will synthesize double-doped rare-earth perovskite-type porous nanotubes as LNT catalysts. The porous wall of nanotubes can increase the specific surface area and the hollow structure can relieve the structure destruction from volume change. The effects of specific surface area, hollow structure, oxygen vacancies and Fe doping content on its LNT catalytic performance and sulfur tolerance will be studied with the help of characterization techniques. Finally, the structure-activity relationship of LNT catalyst is clearly revealed. The successful implementation of this project will serve theoretical basis and experimental evidences for the design and development of high-efficiency and economic LNT catalysts.

稀薄燃烧（简称稀燃）可以提高燃油效率，减少CO2的排放，但是过量的氧气增加了尾气中NOx消除难度。稀燃NOx阱(lean-burn NOx trap, LNT)技术是解决该问题的最有效途径之一。申请人前期研究表明，稀土钙钛矿(ABO3)具有可媲美贵金属催化剂的LNT活性，通过碱性金属对A位的掺杂可以增加氧空位浓度，进一步提高其催化性能；通过Fe元素对B位的掺杂可以提高其抗硫性能。但是传统钙钛矿存在比表面积较小，稀/富燃循环中结构易破坏等问题。.针对上述问题，本项目拟制备双掺杂稀土钙钛矿型多孔纳米管LNT催化剂，利用多孔管壁增加比表面积；利用中空结构克服体积变化引起的结构破坏。结合多种表征技术，详细考察比表面积，中空结构，氧空位浓度和Fe掺杂量对LNT催化及抗硫性能影响，阐明催化剂的构效关系。项目的顺利实施将为设计开发高效实用的LNT催化剂提供理论基础和实验依据。

发展高效的柴油车尾气净化催化剂并实现目标材料的精准合成是无机化学与环境催化化学领域的重要挑战。本项目设计合成了负载型复合金属氧化物多孔纳米片阵列，发展了一种协同调控钙钛矿氧化物中氧缺陷浓度的新方法，构建了核@壳结构Mn3O4@CaMn7O12纳米棒，通过结合多种表征手段研究了材料的尺寸、孔结构及氧空位浓度对催化剂的氧活化能力及宏观催化碳烟消除性能的影响，建立构效关系，加深对于soot催化消除机理和动力学的理解。开发出起燃温度为321oC的高效soot消除催化剂。项目负责人在本项目资助期间，入选天津市“131”创新型人才培养工程第三层次人选（2019年），天津市高校“青年后备人才培养计划”（2019年），荣获天津工业大学2019年青年教师教学竞赛（工科组）二等奖，2020年10月被聘为副教授。