| Summary: | Catalysts with no hazardous or toxic components are required for the selective hydrogenation of acetylenic bonds in the synthesis of pharmaceuticals, vitamins, nutraceuticals, and fragrances. The present work demonstrates that a high selectivity to alkene can be reached over a Pd-Fe-O/SiO<sub>2</sub> system prepared by the co-impregnation of a silica support with a solution of the metal precursors (NH<sub>4</sub>)<sub>3</sub>[Fe(C<sub>2</sub>O<sub>4</sub>)<sub>3</sub>] and [Pd(NH<sub>3</sub>)<sub>4</sub>]Cl<sub>2</sub> followed by thermal treatment in hydrogen or in air at 400 °C. A DRIFT spectroscopic study of CO adsorption revealed large shifts in the position of the Pd<sup>n+</sup>-CO bands for this system, indicating the strong effect of Fe<sup>n+</sup> on the Pd electronic state, resulting in a decreased rate of double C=C bond hydrogenation and an increased selectivity of alkyne hydrogenation to alkene. The prepared catalysts consisted of mono- and bimetallic nanoparticles on an SiO<sub>2</sub> carrier and exhibited a selectivity as high as that of the commonly used Lindlar catalyst (which contains such hazardous components as lead and barium), while the activity of the Fe-Pd-O/SiO<sub>2</sub> catalyst was an order of magnitude higher. The hydrogenation of a triple bond over the proposed Pd-Fe catalyst opens the way to selective hydrogenation over nontoxic catalysts with a high yield and productivity. Taking into account a simple procedure of catalyst preparation, this direction provides a rationale for the large-scale implementation of these catalysts.
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