Catalytic reaction sites that uniquely behaves geometrically and electronically have found its own area of study in the field of catalyst design, synthesis, and characterization. The generalizable, facile synthesis method of strong electrostatic adsorption is pushed to the limit of metal dilution to prepare single atom sites on a supported cluster of another metal. This category of well dispersed atoms alloyed on a metal surface have shown unique functionality for reactions like selective hydrogenation of alkynes and dienes to alkenes, ethanol dehydrogentation, and the Ullmann reaction of aryl chlorides. Flytzani-Stephanopulos et. al. (2013) prepared such nanoparticles on an alumina support via galvanic displacement of Cu by Pd. This method is limited to only those systems which possess the correct reduction potentials. In the current work, we present a generalizable method to prepare an infinitely dilute alloy of one metal in another via simultaneous strong electrostatic adsorption (co-SEA). Wong et. al. (2017) successfully synthesized silica supported, ultrasmall, homogeneously alloyed bimetallic catalyst at 1:1 atomic ratio by co-SEA. In the same manner, we extend the method to the dilution limit of one or two atoms in a crystallite of 30 or 40 atoms. The various combinations of representative metals (Ru, Pd, Pt, Ni, Co, and Cu) on high surface area amorphous silica were synthesized and characterized using high sensitivity powder x-ray diffraction, aberration-corrected electron microscopy, temperature programmed reduction, X-ray photoelectron spectroscopy and FTIR spectroscopy. Catalyst activity and selectivity was tested on hydrogenation reaction involving of biomass derived oxygenated hydrocarbon.

Simultaneous strong electrostatic adsorption (co-SEA) for the facile synthesis of supported, dilute limit alloy bimetallic catalysts

ACS Fall 2021

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