Heterogeneous catalytic reactions play a crucial role in the synthesis of 90% of all feedstock chemicals. In recent years, high-temperature reactions that allow for more direct and energetically efficient synthesis pathways, such as the Catalytic Partial Oxidation (CPO) of methane to syngas or the Oxidative Coupling of Methane (OCM) to obtain ethylene, have received increasing attention. Both processes are still in the research stage and are not employed commercially, so the technical development of catalysts with sufficient selectivity and high process stability is of great importance. In order to improve the general understanding and the models of numerical simulations, experimental data is needed that represents not only the heterogeneous reaction at the surface of the catalyst but also the gas-phase co-reactions that occur due to the high temperatures in the range of up to 1300 K and short contact times. Spontaneous Raman spectroscopy is particularly suitable for diagnosing these gas-phase reactions, as it allows the complete thermo-chemical state (all main species concentrations and the local temperature) to be accessed simultaneously, in-situ and non-intrusively. However, the extreme process conditions pose challenges for spectroscopic measurement techniques, such as the broadband thermal radiation emitted from the walls of the flow channel, which spectrally overlaps the actual Raman scattering.
