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Free keywords:
REDUCTION; PLATINUM; SURFACES; PTFE; PD; OXIDATION; KETONES; SYSTEM;
ALLOYS; ACIDScience & Technology - Other Topics; Materials Science; bimetallic nanoparticles; supported ionic liquid phases; platinum; iron;
hydrogenation; hydrodeoxygenation; catalysis; magnetism;
Abstract:
Iron-platinum nanoparticles of tunable Fe/Pt ratios were immobilized on an imidazolium-based supported ionic liquid phase (SILP). The resulting FexPt100-x @SILP materials were characterized and applied in catalysis. Electron microscopy confirmed the formation of small, well-dispersed, bimetallic nanoparticles in all the investigated materials. Magnetometry measurements evidenced a clear influence of the Fe/Pt ratio on the oxidation state of Fe in FexPt100-x @SILP. In particular, Fe appeared in the metallic state at x <= 40, whereas partial oxidation was observed at x >= 60. The catalytic properties of FexPt100-x @SILP materials were probed using the reduction of benzylic ketones with H-2 as a model reaction. The Fe/Pt ratio of the nanoparticles was found to have a critical influence on the observed activity and selectivity, with clear synergistic effects. In particular, by diluting Pt with Fe sites, the ability of FexPt100-x @SILP catalysts to hydrogenate 6-membered aromatic rings was shut down for x >= 40, while C=O hydrogenation activity was preserved. In addition, Fe40Pt60@SILP showed excellent hydrodeoxygenation activity and selectivity with acetophenone derivatives in the absence of acid additives. This remarkable reactivity, out of reach for monometallic Pt@SILP, is attributed to the enhanced oxophilicity of Fe in FePt catalysts favoring C=O activation and cleavage.
