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Stable Ordered FePt Mesoporous Silica Catalysts with High Loadings

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journal contribution
posted on 12.08.2008, 00:00 by Gaurav Gupta, Mehul N. Patel, Domingo Ferrer, Andrew T. Heitsch, Brian A. Korgel, Miguel Jose-Yacaman, Keith P. Johnston
A new concept is presented to form catalysts by infusion of presynthesized bimetallic nanocrystals into ordered mesoporous supports. For presynthesized FePt nanocrystals (<4 nm) coated with oleic acid and oleylamine ligands in toluene, high loadings above 10 wt % were achieved in 10 min. The strong metal−support interactions were favored by the low coverage of the weakly bound ligands. The nanocrystals were highly dispersed within the pores as indicated by HAADF-STEM and X-ray diffraction (XRD) and stable against sintering at 700 °C and desorption into polar and nonpolar solvents at room temperature. A phase transformation from a disordered phase (FCC) to ordered phase (FCT) was observed upon thermal annealing at 700 °C without sintering, as confirmed by convergent beam electron diffraction and XRD. The calcined FePt catalyst exhibited 6-fold higher catalyst activity (TOF = 30 s−1) than that of a commercial Pd-alumina catalyst for liquid 1-decene hydrogenation and was stable for multiple reactions. The decoupling of nanocrystal synthesis and infusion provides exquisite control of the nanocrystal size, alloy structure, binding to the support and dispersibility within the pores, offering broad opportunities for enhanced catalyst activities, selectivities, and stabilities.