Gas-phase Raman spectroscopy for two-dimensional temperature and concentration profiling in the catalytic oxidative dehydrogenation of ethanol
Koschnick K, Ferris AM, Stark M, Stark D, Welzenbach J, Winkler N, Weinmann A, Hess C, Etzold B, Drochner A, Franken T, Geyer D, Dreizler A (2026)
Publication Type: Journal article
Publication year: 2026
Journal
Book Volume: 712
Article Number: 120767
DOI: 10.1016/j.apcata.2025.120767
Abstract
A novel optically accessible catalysis flow channel is introduced that enables quantitative, contiguous, two-dimensional in situ measurements of gas-phase temperature and species concentrations during heterogeneous catalytic reactions. Spatially resolved gas-phase Raman spectroscopy, integral Fourier-transform infrared spectroscopy, and catalyst-resolved infrared thermography establish a well-defined platform for studying coupled reaction–transport phenomena. Applied to the oxidative dehydrogenation of ethanol over iron–molybdenum oxide catalysts, spontaneous Raman measurements yielded two-dimensional profiles of nine gas-phase species – with limits of detection in the tens-to-hundreds-of-ppm range – and gas-phase temperature within 500µm of the catalyst surface. Transport analysis in the boundary layer yielded a Lewis number of approximately 1.65, indicating dominant thermal diffusion near the surface, while axial Péclet numbers revealed diffusion-controlled heat transport but advection-dominated product transport in a laminar regime. Varying the bulk flow velocity did not significantly alter conversion or product distributions, indicating kinetic and diffusive control under the present conditions. An iron-rich catalyst formulation exhibited higher activity than stoichiometric Image 1001, whereas temperatures above 511K reduced selectivity due to increased formation of total-oxidation products. Catalyst-free experiments, supported by kinetic simulations, confirmed partial gas-phase oxidation of acetaldehyde to CO, CO2, acetic acid, methanol, formaldehyde, and peracetic acid. These results highlight the importance of local gas-phase contributions and demonstrate that spatially resolving the gas-phase thermochemistry enables the gas phase to act as a reporter of surface reactions and facilitates the decoupling of chemical processes from transport phenomena.
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APA:
Koschnick, K., Ferris, A.M., Stark, M., Stark, D., Welzenbach, J., Winkler, N.,... Dreizler, A. (2026). Gas-phase Raman spectroscopy for two-dimensional temperature and concentration profiling in the catalytic oxidative dehydrogenation of ethanol. Applied Catalysis A-General, 712. https://doi.org/10.1016/j.apcata.2025.120767
MLA:
Koschnick, Konrad, et al. "Gas-phase Raman spectroscopy for two-dimensional temperature and concentration profiling in the catalytic oxidative dehydrogenation of ethanol." Applied Catalysis A-General 712 (2026).
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