钯{hkl}纳米晶的非平衡可控生长及在三效催化剂中的应用

Palladium nanocrystals are highly effective in the catalytic oxidation of CO in low operating temperature, and are promising catalysts for abatement from gasoline engine exhaust. This program is focused on the improvement of the former Pd-based three way catalyst, by introducing an autocatalytic chemical system in the synthesis of Pd{hkl} nanocrystals, in which the size and structure of Pd{hkl} nanocrystals is controlled by the oscillating concentration of bromide ions, and such reaction procedure is monitored by in situ electrochemical measurement. By applying transmission electron microscope, X-ray photoelectron spectroscopy and X-ray Diffraction methods, the structure and composition of Pd{hkl} will be clarified. By utilizing in situ fourier transform infrared spectroscopy and photoemission electron microscope methods, the relationship between the CO catalytic activity and active sites on perimeter and surface of Pd{hkl} nanocrystals will be investigated comprehensively. Based on the experimental results of CO catalytic oxidation, a micro-kinetic reaction model will be established for revealing the rate-determined steps and important intermediates. These results will provide fundamental understandings for the contribution ratio of varied active sites on the perimeter and surface of Pd{hkl} nanocrystals, and will establish theoretical basis for applicable new three way catalyst satisfying Euro VI emission criteria.

钯纳米晶催化剂对CO具有优异的低温催化性能，有望应用于汽车尾气中CO的催化净化。本项目针对前期项目组开发的单钯三效催化剂进行升级改造，将新的钯{hkl}纳米晶制备技术引入催化剂的制备当中，利用自催化化学体系中溴离子晶面控制剂浓度的周期性变化对钯{hkl}纳米晶进行可调控生长，此反应进程及各反应物种浓度之间的关联可以用原位电化学的方法进行测定，并利用透射电子显微镜(TEM)、X射线光电子能谱(XPS)、X射线衍射(XRD)等检测手段分析钯纳米晶的结构与组成，结合原位红外、光发射电子显微镜(PEEM)等表征手段，深入研究钯纳米晶催化氧化CO的构效关系，通过微观动力学的实验测试及模拟分析，详细研究CO在钯{hkl}纳米晶上的反应机理及中间产物，研究钯{hkl}纳米晶催化活性中心的贡献比例。通过本研究工作为开发实际应用于欧VI排放标准的新型三效催化剂提供关键技术的储备和支撑。

棱线周长最长的Pd{hkl}纳米晶催化剂对CO具有优异的低温催化性能，有望应用于汽车尾气中CO的催化净化性能。本项目针对前期项目组开发的单钯三效催化剂进行升级改造，将新的钯纳米晶制备技术引入催化剂的制备当中，利用自催化化学体系中溴离子晶面控制剂浓度的周期性变化对Pd{hkl}纳米晶进行可调控生长，此反应进程及各反应物种浓度关联可以用原位电化学的方法进行测定，并利用透射电子显微镜(TEM)、X射线光电子能谱(XPS)、X射线衍射(XRD)等检测手段分析钯纳米晶的结构与组成，结合原位红外、光发射电子显微镜(PEEM)等表征手段，深入研究钯纳米晶催化剂催化氧化CO的构效关系，通过微观动力学的实验测试及模拟分析，详细研究CO在钯{hkl}纳米晶上的反应机理及中间产物，研究钯{hkl}纳米晶催化活性中心的贡献比例。通过本研究工作为开发实际应用于欧VI排放标准的新型三效催化剂提供关键技术的储备和支撑。