碳微球模板法介孔CeZrO2制备及催化氧化汽油车碳烟性能研究

Soot particulate matter (PM) is one of the main pollutants in vehicle exhaust, which is harmful to human health and the environment. Catalytic oxidation is an effective way to eliminate soot. However the high temperature and low oxygen working environment of gasoline vehicles exhaust make the research of soot oxidation catalyst extremely challenging. Regular mesoporous CeZrO2 catalysts can simultaneously possess the excellent redox performance as well as high thermal stability of CeO2-based catalyst and good contact efficiency of three-dimensional ordered macroporous (3DOM) catalysts, which is expected to catalyze soot oxidation efficiently. How the preparation process of carbon nanospheres template and CeZrO2 catalysts make impacts on microstructure of catalysts and thus their high temperature stability as well as contact efficiency will be investigated; in addition, the influence of Zr doping process on oxygen storage performance and oxygen mobility, as well as the matching relationship between mesoporous size and soot contact efficiency is also to be investigated; and thus developing excellent regular mesoporous CeZrO2 catalysts. Furthermore, the influence of different experimental parameters on catalysts' activities will be investigated to get the catalytic reaction law and the microcosmic kinetic equation, and then propose the reaction mechanism. Correlation kinetic data, microstructure and preparation process is to clarify the essential relationship among catalyst preparation process, microstructure and catalysts performance; is to master the effective means to improve the performance of catalysts, and establish the regulation mechanism of catalyst preparation which can provide key technical reserves and important theoretical basis for the design, preparation and structure optimization of soot oxidation catalysts.

碳烟颗粒物（PM）是机动车尾气主要污染物之一，对人体健康和环境危害极大。催化氧化是消除碳烟的有效途径，但汽油车高温、低氧的尾气环境使碳烟氧化催化剂的研究极具挑战性。规则介孔CeZrO2催化剂兼有CeO2基催化剂优异的氧化还原性能、高温稳定性和三维有序大孔催化剂的高接触效率，有望高效催化氧化碳烟。研究碳微球模板剂和CeZrO2制备过程与微观结构的关系及对高温稳定性和接触效率的影响规律；研究Zr掺杂过程对储氧性能及氧移动性的影响；研究介孔尺寸与碳烟接触效率的匹配关系，制备出高性能规则介孔CeZrO2催化剂。研究不同实验参数对催化剂活性的影响，获得催化反应规律和动力学方程，提出反应机理。关联动力学数据-微观结构-制备过程，明确制备过程、结构与反应性能间的本质联系；掌握改善催化剂性能的有效手段，建立催化剂制备的调控机理，为碳烟氧化催化剂的设计、制备与结构优化提供关键技术储备和重要的理论依据。

颗粒物是造成雾霾的主要原因之一，对人体健康和环境危害极大。汽油车尾气碳烟颗粒物数量大、粒径小，且净化催化剂服役环境极端苛刻（高温，低氧）；极难消除。设计构筑兼具高温稳定性和优异氧化还原性能，同时具有合适孔结构的催化材料是突破苛刻服役工况下汽油车颗粒物净化技术的关键。本项目（1）发展了聚甲基丙烯酸甲酯微球和聚（丙烯腈-co-苯乙烯）共聚物微球，并以此为模板，实现了不同孔径及不同贯穿孔径结构CeO2及CeZrO2催化剂的可控制备，明显改善了传统微介孔CeZrO2催化剂与碳烟的接触效率，提升了催化活性，碳烟T90降低了90 oC（较商业催化剂）；（2）以制备的CeZrO2为基础，利用发展的配位还原法调控贵金属微化学环境，协同表面活性剂竞争吸附浸渍法掺杂助剂等手段，构筑出高活性高稳定性低起燃Pt/CeZrO2-re催化剂，有效改善了低温下气相氧的吸附-活化能力（活性氧的产生与传输），进一步优化了Pt/CeZrO2催化剂活性，碳烟T90再降低30 oC，低至367 oC；（3）综合利用多种表征手段分析催化剂性质、反应气氛、孔径结构、贵金属微化学环境等对催化剂碳烟氧化活性的影响规律，阐明了不同反应气氛下碳烟氧化遵循的反应机理（详细机理见正文），提出接触效率和气相氧的吸附与活化是制约低氧浓度下碳烟氧化的关键因素，并提出协同优化孔径结构-调控贵金属微化学环境-助剂辅助等多角度改善接触效率及活性氧产生与传输能力的综合策略，进而提升催化剂碳烟氧化性能，实现了碳烟氧化催化剂的可控制备。基于上述研究成果，发表学术论文5篇，申请发明专利1项，参编专著1本，获准四川省科技进步二等奖1项。同时，本项目发展的催化材料和催化剂技术在产学研合作公司得到了应用；研发的碳烟氧化催化剂已成功搭载三效催化剂，用于满足国VI排放标准的低温高活性汽油车尾气催化剂系统，成功产业化。