Supported Catalytically Active Liquid Metal Solutions (SCALMS) for Propane Dehydrogenation–Intermetallic Phases and Liquid Alloys Studied by Pair Distribution Function Analysis and Density Functional Theory

The supported catalytically active liquid metal solution (SCALMS) concept is based on catalytically active metals dissolved in a low-melting-point liquid metal matrix. These solid alloy particles, deposited over a high area support, transform into a liquid alloy under reaction conditions. In this work, GaPt SCALMS materials of varying composition are investigated and focus on the change in the alloy composition during preheating, the actual high temperature propane dehydrogenation at 823 K, and after cool-down. X-ray diffraction (XRD) is used and analyze the pair distribution function (PDF) combined with density functional theory (DFT) studies. Before catalysis, the Ga phase oxidizes to an amorphous β-Ga₂O₃ phase which is likely removed during activation. Refinements for all sample data before catalysis confirm the presence of fcc-Pt nanoparticles. After catalysis, the Pt nanoparticles convert to a GaPt₂ alloy phase with high structural disorder, visible in the difference pair distribution function (dPDF). The machine-learned force fields (ML-FF) simulations suggest that GaPt₂ forms at the Pt(111) interface with liquid Ga through gradual Ga intercalation into the Pt crystal structure. Simulations further indicate that both fcc-Pt and GaPt₂ are stable at temperatures up to 800 K if the Pt content of the surrounding liquid is high enough.