In Situ Raman Spectroscopy of Supported Catalytically Active Liquid Metal Solutions (SCALMS)—Activation and Coking Behavior in Propane Dehydrogenation

Abstract Supported catalytically active liquid metal solutions (SCALMS) represent a new class of catalysts characterized by a highly dynamic catalytic interface due to the liquid state of the active phase. In this study, we have investigated the relevance of H 2 pre‐reduction treatment of Ga–Pt SCALMS in propane dehydrogenation reaction (PDH). To elucidate the role of hydrogen during pretreatment and the reason for catalyst deactivation, in situ Raman spectroscopic characterization of silica‐supported Ga–Pt SCALMS catalysts was carried out during PDH at 823 K. The results demonstrate that the native passivating ß‐Ga 2 O 3 skin present in fresh Ga–Pt SCALMS catalyst can be effectively reduced via pretreatment with hydrogen at 823 K. The presence of Pt is crucial for the reduction. With the onset of the PDH reaction, the in situ Raman spectra show the formation of graphitic coke over the applied Ga–Pt‐based SCALMS catalysts, which is at least partly due to the reactivity of the applied support material or due to some remaining gallium oxide present in the system. Over long time on stream, the formed graphitic coke accumulates, eventually leading to deactivation of the catalyst.