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Continuous-flow reactor setup for operando x-ray absorption spectroscopy of high pressure heterogeneous liquid-solid
Benedikt J Deschner1, Dmitry E Doronkin2, Thomas L Sheppard2
1Institute for Micro Process Engineering, Karlsruhe Institute of Technology, Hermann-von-Helmholtz-Platz 1, Eggenstein-Leopoldshafen 76344, Germany.
The Review of Scientific Instruments
|January 1, 2022
Summary
A new continuous-flow reactor enables safe, in-situ X-ray absorption spectroscopy (XAS) studies of liquid-phase reactions on transition metal catalysts. This system allows detailed analysis of catalyst structure and activity under high pressure and temperature conditions.
Area of Science:
- Chemical Engineering
- Materials Science
- Spectroscopy
Background:
- Studying liquid-phase reactions on solid catalysts requires specialized equipment for in-situ analysis.
- High-pressure and high-temperature conditions are crucial for many catalytic processes but pose safety challenges.
- Operando X-ray absorption spectroscopy (XAS) provides detailed insights into catalyst behavior during reactions.
Purpose of the Study:
- To design and validate a continuous-flow reactor system for operando XAS studies.
- To enable safe investigation of liquid-phase reactions on transition metal catalysts under elevated pressures and temperatures.
- To facilitate detailed studies on catalyst structure-activity relationships.
Main Methods:
- Development of a continuous-flow reactor with PEEK windows and low internal volume (0.31 ml).
- Integration of the reactor into an operando XAS setup with wide-angle beam access for complementary X-ray techniques.
- Engineering for safe, single-phase liquid flow and homogeneous reactant saturation.
- Proof-of-concept using operando XAS during hydrogen peroxide synthesis with Pd/TiO2 catalyst.
Main Results:
- The designed reactor and setup safely accommodate liquid-phase reactions up to 100 bars and 100 °C.
- High-quality XAS data were obtained during the direct synthesis of hydrogen peroxide.
- The system demonstrated suitability for real-time monitoring of catalytic reactions in the liquid phase.
- Successful integration of inline near-infrared spectroscopy for complementary reaction monitoring.
Conclusions:
- The developed continuous-flow XAS system is well-suited for studying liquid-phase catalytic reactions under demanding conditions.
- This technology paves the way for in-depth investigations into catalyst structure and its correlation with activity.
- Enhanced process safety and sample homogeneity were achieved through the reactor design.
