NanoFunC - Controlling Selectivity via Nanostructuring of Multifunctional Model Catalysts

未来的愿景是合理设计具有更高选择性和活性的纳米结构催化剂材料。为此，我们探索了甲烷二氧化碳重整和二氧化碳氧化偶联的基础模型研究的潜力。受到涉及多功能材料的经验方法的启发，新型多纳米结构模型催化剂被开发出来，例如，在定义明确的环境中集成(A)氧化还原中心(例如CeO2)(B)碱性中心(例如MgO，BaO)，(C)金属中心(例如Rh，Pt)和(D)载体中心(例如Al_2O_3)。该项目的三步战略基于独特的实验技术组合：(I)在超高真空(UHV)条件下制备多纳米结构模型表面及其结构和化学性质(颗粒结构、尺寸、密度、缺陷、边界位置、复合/隔离纳米颗粒等)。使用超高真空显微镜和广泛的表面科学方法对其进行了详细的表征。(Ii)应用分子束(MB)技术和时间分辨表面光谱技术，在微观水平上将结构性质与所选关键步骤的基本反应动力学、能量学和动力学相关联。(3)最后，将有关纳米结构和基本动力学的信息与系统和定量的动力学研究结合起来，应用多MB方法、反应堆方法和从超高真空到环境条件(“压力间隙”)的时间分辨原位表面光谱分析。在这三个步骤中，实验研究与高水平的DFT(密度泛函理论)计算紧密相连，这些计算使用了最近开发的先进的纳米结构反应系统的现实模型，允许对后者进行充分的描述。该项目的目的是开发微观上有充分基础的机理模型，提供对完整反应系统的一致描述。这些模型将明确地包括纳米结构的动力学控制和多纳米结构系统中动力学效应的相互作用。对于CO2重整和CO2-OCM，通过纳米结构优化选择性是最有意义的，包括例如通过动力学抑制碳形成来控制失活等方面。除了对这些特定的目标反应做出重大贡献外，该项目还将产生概念性的见解，指导未来针对定制的纳米结构催化剂的设计策略。

A future vision is the rational design of nanostructured catalyst materials with improved selectivity and activity. Towards this aim we explore the potential of fundamental model studies in CO2-reforming and CO2-OCM (oxidative coupling) of methane. Inspired by empirical approaches involving multifunctional materials, novel multiply nanostructured model catalysts are developed, which integrate, for instance (a) redox sites (e.g. CeO2) (b) basic centres (e.g. MgO, BaO), (c) metallic sites (e.g. Rh, Pt) and (d) support sites (e.g. Al2O3) in a well-defined environment. The three-step strategy of this project is based on a unique portfolio of experimental techniques: (i) Multiply nanostructured model surfaces are prepared under UHV (ultrahigh vacuum) conditions and their structural and chemical properties (particle structure, size, density, defects, boundary sites, composite/isolated nanoparticles, etc.) are characterized in detail using UHV microscopies and a broad spectrum of surface science methods. (ii) The structural properties are correlated with elementary reaction kinetics, energetics and dynamics of selected key steps at the microscopic level, applying MB (molecular beam) techniques and time-resolved surface spectroscopies. (iii) Finally, the information on nanostructure and elementary kinetics is combined with systematic and quantitative kinetic studies, applying multi MB methods, reactor methods, and time-resolved in-situ surface-spectroscopies from UHV to ambient conditions (“pressure gap”). In all three steps, the experimental studies are closely linked with high-level DFT (density functional theory) calculations employing advanced recently developed realistic models of nanostructured reaction systems, which allow for adequate description of the latter.The aim of the project is to develop microscopically well-founded mechanistic models, which provide a consistent description of the complete reaction system. These models will explicitly incorporate kinetic control by nanostructuring and the mutual interplay of kinetic effects in multiply nanostructured systems. With respect to CO2-reforming and CO2-OCM the optimization of selectivity by nanostructuring is of primary interest, including aspects such as e.g. controlling deactivation by kinetically suppressing carbon formation. Beyond strong contribution to these specific target reactions, the project will result in conceptual insights guiding future design strategies towards tailor-made nanostructured catalysts.