In-House X-ray Absorption Spectrometer

X射线吸收光谱(XAS)是一种有用的技术，可以在几乎任何条件下(固体、液体、溶液、无定形、结晶、高温、低温、高压等)表征多种形式的功能分子和材料(尤其是催化剂)。XAS是特定于元素的，提供了有关所选元素的电子结构和原子连接性的信息，基本上不受材料其余部分的干扰。这使得它在研究复杂的催化反应方面特别受欢迎。尽管XAS具有实用价值，但它一直受到测量困难的阻碍，直到最近，测量只能在少数几个同步辐射设施中的一个进行。由于缺乏测量时间，获得测量时间的耗时过程(必须提前一年左右申请)以及此类设施提供或批准的测量时间有限(通常只有3-5天)，往往既无法测量常规样品，也无法对重要催化过程进行长期的现场测量。这往往阻碍了有用的项目的实施和有趣的工作的发表。自2015年以来，市场上一直有内部XAS光谱仪，它们能够在不使用同步加速器的情况下测量高质量的XAS光谱。斯图加特大学没有这样的仪器，这将填补目前用于表征催化剂和功能材料的仪器能力方面的进展限制空白。该仪器将使某些实验成为可能(例如，长达数周的非均相催化剂的原位测量，对空气敏感的均相催化剂体系的原位测量)，这些实验到目前为止要么是不可能的，要么是不切实际的。这无疑也将带来更多、更高质量和更快的出版物，这是通过消除在同步加速器光束线上获得测量时间的障碍而永远不会出现的。在这项建议中，我们建议配备一台内部X射线吸收光谱仪，用于固相和液态催化剂，能够在整个催化剂寿命过程中测量催化剂的X射线吸收光谱，用于二氧化碳转化、大环和聚合物合成，以及不对称有机反应。这将使我们能够了解现有工业催化剂的失活机理，监测真实反应条件下催化剂的活性物种，并了解反应过程中催化剂物种的电子结构。这样的系统将为现有催化剂系统提供新的见解，并使新技术进入实际应用。

X-ray absorption spectroscopy (XAS) is a useful technique for characterizing functional molecules and materials (especially catalysts) in many forms under nearly any conditions (solid, liquid, solution, amorphous, crystalline, high temperature, low temperature, high pressure, among others). XAS is element-specific and gives information about the electronic structure and atomic connectivity of a chosen element largely without interference from the rest of the material. This makes it especially beloved for studying complex catalytic reactions. Despite its utility, XAS has been held back by the difficulty of performing the measurements, which could until recently only be performed at one of a handful of synchrotron radiation facilities. The time-consuming process of obtaining measurement time (which must be applied for around a year in advance) and the limited amount of measurement time available or granted (often only 3 – 5 days) at such facilities frequently prevents both the measurement of routine samples and long-term in situ measurements of important catalytic processes, due to a lack of measurement time. This often prevents useful projects from being carried out and interesting work from being published.Since 2015, in-house XAS Spectrometers have been on the market that are capable of measuring high quality XAS spectra without the use of synchrotron facilities. Such an instrument is not available at the University of Stuttgart and would fill a progress-limiting gap in the current instrumental capabilities for characterization of catalysts and functional materials. This instrument would make certain experiments possible (e.g. long-term weeks-long) in situ measurements of heterogeneous catalysts, in situ measurements of air-sensitive homogeneous catalyst systems) that up until now were either impossible or impractical. It will also undoubtedly result in more, higher quality and faster publications that would never have otherwise appeared by removing the barrier of obtaining measurement time at synchrotron beam-lines.In this proposal, we propose to outfit an in-house X-ray absorption spectrometer with in situ reactors for both solid and liquid phase catalysts capable of measuring X-ray absorption spectra of catalysts for CO2 conversion, macrocycle and polymer synthesis, and enantioselective organic reactions over the course of the full catalyst lifetimes. This will allow us to understand the mechanisms of deactivation of existing industrial catalysts, monitor the active species of catalysts under real-life reaction conditions, and understand the electronic structure of species during reaction. Such a system will both provide new insights into existing catalyst systems and enable new technologies to enter practical use.