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High-Sensitivity Gas-Phase Raman Spectroscopy for Time-Resolved In Situ Analysis of Isotope Scrambling over Platinum
K Koschnick1,2, A M Ferris1,3, B Zhang4
1Reactive Flows and Diagnostics, Department of Mechanical Engineering, Technical University of Darmstadt, Otto-Berndt-Straße 3, 64287 Darmstadt, Germany.
Analytical Chemistry
|August 13, 2025
Summary
This study introduces a new method using Raman spectroscopy for real-time analysis of isotope scrambling on platinum catalysts. The technique accurately tracks hydrogen isotope reactions, revealing insights into catalytic mechanisms.
Area of Science:
- Catalysis
- Spectroscopy
- Chemical Kinetics
Background:
- Isotope scrambling reactions are crucial in catalysis.
- Understanding reaction mechanisms requires precise, real-time monitoring.
- Platinum nanoparticle catalysts are widely used in chemical transformations.
Purpose of the Study:
- To develop a novel time-resolved, in situ method for analyzing isotope scrambling reactions.
- To investigate the reaction mechanisms of hydrogen isotopes over platinum nanoparticle catalysts.
- To quantify gas-phase mole fractions with high sensitivity and accuracy.
Main Methods:
- Utilized high-sensitivity gas-phase Raman spectroscopy with a newly developed spectrometer.
- Introduced D2 gas to an H2-activated Pt nanoparticle catalyst in a closed system.
- Employed a spectral fitting routine with simulated Raman spectra for quantification.
Main Results:
- Observed HD as the dominant product, indicating a predominantly associative exchange mechanism.
- Detected superimposed water vapor exchange, showing stepwise conversion of H2O to D2O.
- Achieved relative accuracies better than 2% and convergence of reaction quotients to equilibrium constants.
Conclusions:
- The developed Raman spectroscopy method allows simultaneous, in situ detection of all relevant species.
- This technique is highly suitable for studying transient catalytic processes with high accuracy.
- The findings provide detailed insights into hydrogen isotope scrambling mechanisms on platinum catalysts.
