Shining light on low-temperature methanol aqueous-phase reforming using homogeneous Ru-pincer complexes – operando Raman-GC studies

Abstract

A Ru-pincer-based system, which enables methanol dehydrogenation at ambient pressure and temperatures below 100 °C in an aqueous alkaline solution, was investigated as a basis for a possible hydrogen supply process design. A combined in situ liquid-phase Raman spectroscopy with online gas chromatography (GC) analysis of the effluent gas-phase was used to detect the reaction intermediates and effluent gases. Formate (HCOO⁻) was detected as an intermediate and its qualitative concentration profile could be derived from the Raman spectrograms. In addition, the Raman signal's intensity revealed the initial formation of solid potassium carbonate in the liquid phase, which corresponds with the first detection of carbon dioxide in the gas phase based on the GC results. The combination of in situ Raman spectroscopy and online GC proved to be a powerful experimental setup that provided a holistic view on this complex reaction mechanism.