In-House X-ray Absorption Spectrometer

• Subject Area: Process Engineering, Technical Chemistry
• Term: Funded in 2022
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 495153105

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.

• DFG Programme: Major Research Instrumentation
• Major Instrumentation: "In-House" Röntgenabsorptionsspektrometer
• Instrumentation Group: 4030 Röntgenfluoreszenz-Spektrometer
• Applicant Institution: Universität Stuttgart
• Leader: Professor Dr. Deven Estes