Fiber-coupled Raman spectroscopy for efficient vapor-liquid equilibria characterization: RaceVLE

• Applicant: Professor Dr.-Ing. Hans-Jürgen Koß
• Subject Area: Chemical and Thermal Process Engineering
• Term: since 2021
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 471272247

Accurate data on material properties are the basis for modern model-based process engineering. The lack of adequate vapor-liquid equilibria (VLE) data, represents a major bottle-neck in chemical engineering. To put the reasons in a nutshell: current simulation tools are often inaccurate, while common experimental methods are complex, cumbersome, and resource-inefficient.This project is dedicated to the development of a new scientific device for the rapid and efficient provision of multi-component VLE data by optical laser-based Raman spectroscopy (RS). Equilibria are formed in an optically accessible static equilibrium cell and are characterized non-intrusively and remotely by RS. This approach offers various benefits, as shown in our previous works. These benefits include short measurement times, minimal substance consumption, and access to reliable datasets without physical sampling.However, to establish the techniques as the new standard method for VLE data provision, we see the need for further developments based on our proof-of-principle setup. The specific design requires expensive optical components, optical laboratories, and operators with profound knowledge on optics to set up and run the experiments. These factors hamper the widespread application of this promising technique.The central goal of this project is to lower these barriers and prerequisites in order to increase the accessibility and value of the technology for as many researchers as possible. We focus on developing a compact demonstrator to pave the road for broader distribution or even commercialization of the technique. As for other devices, the key strategies for enabling widespread dissemination are simplification, automation, modularization, and reliability. These four elements are targeted through different means within this project. The optical as well as the mechanical setup, will be streamlined. As an example, fibers will substitute free light paths, increasing the robustness and enabling the use outside of distinct optical laser laboratories. Specifically designed and optimized signal generation and detection paths for the VLE phases lead to high-quality Raman spectra that allow precise quantification of the phase compositions. The measurement procedure will be automated, including loading the device with substances, controlling the equilibration process, and recording and evaluating the Raman measurements.The resulting demonstrator will be used for the in-house provision of VLE-data, e.g. within our DFG cluster of excellence, the RWTH fuel science center (FSC). Research and development departments in industry or academia interested in VLE data provision (see attached letter of support) will benefit from our anticipated open-source publications on the apparatus as well as on new VLE data that will be acquired within the final phase of this project.

• DFG Programme: New Instrumentation for Research
• Co-Investigator: Leo Alexander Bahr