RhOx/CeO2催化剂的表界面结构及其催化作用的理论与实验研究

理论研究催化剂处理条件、活性组分粒子尺寸、载体结构等因素对催化剂表界面结构的影响对催化剂理性设计具有重要意义。目前，由于效率问题，密度泛函理论方法难于计算与实际催化剂尺寸匹配的模型；同时非原位、高真空TEM/XPS表征结果与催化剂真实信息差别较大，导致理论与实验结果可比性降低。本项目选择重要应用价值的RhOx/CeO2体系，将最新高效理论方法与原位近常压TEM/XPS表征结合，通过计算不同O/Rh比、RhOx尺寸在载体不同晶面上的结构，结合分子动力学模拟及原位近常压TEM/XPS表征，建立气氛-RhOx尺寸-载体晶面-催化剂结构间的定量关系。通过计算探针分子在RhOx、载体及界面的吸附反应行为，结合实验结果，获取催化剂的活性中心与反应机理，为开发低温高效催化剂提供依据。本项目的研究方法对金属及氧化物纳米粒子负载型催化剂有普适性，为催化研究从炒菜模式走向理性设计进行研究方法的探索与数据积累。

Theoretical investigation of the effects of catalyst treatment conditions, particle sizes of active component and support structures on the catalyst structures is of great significance for the theoretical design of catalysts. However, density functional theory is difficult to calculate the practical catalyst model for the low efficiency; meanwhile the catalyst structure information obtained by the ex-situ TEM/XPS at the ultra high vaccum is greatly different from those in the practical conditions. This reduces the comparability of theoretical predictions and experimental results. To solve these problems, the RhOx/CeO2 catalysts with an important industrial application are chosen in the present work. Using the newly developed theoretical method with high efficiency and the in-situ ambient pressure TEM/XPS techniques, the structures of RhOx/CeO2 catalysts with different O/Rh ratios, RhOx particle sizes and ceria surfaces are systematically optimized. Correspondingly, the quantitative correlations among the treatment atmosphere, particle sizes of RhOx, ceria surfaces and the structures of RhOx/CeO2 are established by combining with the molecular dynamics simulation and catalyst characterization of in-situ ambient pressure TEM/XPS. Based on the adsorption and reaction behaviors of probe molecules on RhOx, CeO2 and their interface, the active sites and reaction mechanism are deduced by combining with the experimental results. This work provides important information for the development of catalysts with high efficiency at the relatively low temperature. Furthermore, the method in this work is widely suitable for the catalyst study of metal and oxide nanoparticles on supports. This work will also provide a research method and data accumulation for catalytic research from the trial-and-error mode to theoretical design at the molecular level.