贫燃钙钛矿电化学催化剂的氮氧化物储存还原过程研究

项目名称： 贫燃钙钛矿电化学催化剂的氮氧化物储存还原过程研究

项目编号： No.20806056

项目类型： 青年科学基金项目

立项/批准年度： 2009

项目学科： 金属学与金属工艺

项目作者： 李新刚

作者单位： 天津大学

项目金额： 18万元

中文摘要： 钙钛矿型催化剂高温稳定，价格低廉。本项目原计划研制出一种电极材料为钡基钙钛矿（如BaFeO3等）的氮氧化物储存还原（NSR）电化学催化剂，用于消除稀燃发动机尾气中氮氧化物（NOx），然而由于电极膜需要在1200℃#20197;上烧结才具有导电性，导致其NOx催化消除效率较低。同时，我们发现BaFeO3催化剂本身即具有优秀的氮氧化物储存和消除性能，在钙钛矿B位掺杂少量的Ti元素后可以大幅度提高其比表面积，NOx储存量也从150umol/g提高到1000umol/g，同时其抗硫性能也得到了大幅度提高：NOx储存量的减少量从13%降低到5%以下。在国际上首次提出并揭示了钡基钙钛矿催化剂在NSR过程中的反应机理，以及B位Fe元素对该催化剂抗硫性提高所起到的重要作用。 在本项目资助下，本课题组已正式发表SCI论文9篇，其中JCR一区论文2篇，2区论文4篇；国内学术期刊发表论文2篇；申请发明专利4项。本项目研制出的是一种潜在的、能够取代贵金属的钙钛矿型NSR催化剂，具有很强的先进性与创新性，能够带来显著的社会效益和经济效益，我们的研究成果目前处于相关研究领域的国际前沿。

中文关键词： 稀燃；钙钛矿；氮氧化物；储存还原

英文摘要： Controlling greenhouse gas emissions and air pollutions is one of the great challenges facing our world. Lean-burn engines can suppress CO2 emission by their high fuel combustion efficiency for mobile vehicles, but NOx is difficultly removed under an oxygen-rich condition because of lacking reductants. A Lean-burn NOx Storage-Reduction (NSR) catalyst, which usually contains expensive noble metals, e.g. Pt, can remove NOx in alternative lean/rich atmospheres. Herein, we report, for the first time, a series of the perovskite-type BaFeO3 catalyst with noble metal free acting as the substitute material for the conventional Pt-containing NSR catalyst. NOx is stored on both perovskite and carbonate, and the formed nitrate on the perovskite can be transferred to the neighboring carbonates to regenerate the storage sites on the perovskite. During the sulfation process, both perovskite and carbonate can be sulfated, and the sulfate species formed on the former one is more easily reduced. The poison of the perovskite catalyst is mainly due to the sulfation of the carbonate. Usually, the NOx storage capacity (NSC) of the conventional Pt/BaO/Al2O3 catalyst drops 40-60% after sulfation pretreatment. The NSC of the sulfated BaFeO3 catalyst, on which only trace amount of carbonate exists, drops only 13 % comparing with the fresh catalyst. It demonstrates that the iron atoms surrounded the barium atoms closely in the crystal lattice of the perovskite inhibit the sulfation of the barium, inducing in a high sulfur tolerance. Moreover, after doping Ti at the B sites, the catalyst's NSC drops less than 5%. The application of the perovskite-type catalysts is a new approach to the future NSR catalyst development with the advantages of decreasing the usage of noble metals, avoiding agglomeration and loss of the active species and possessing a high regeneration ability.

英文关键词： lean-burn; perovskite; NOx; storage-reduction