Selective semi-hydrogenation of alkynes on palladium-selenium nanocrystals

Abstract

The selective hydrogenation of alkyne plays a crucial role in chemical industry, yet great challenges still remain for suppressing the over-hydrogenation to alkane while maintaining high activity. Herein, we demonstrate that palladium–selenium intermetallic nanocrystals (Pd4.5Se NCs, Pd4Se NCs, Pd7Se2 NCs, and Pd7Se4 NCs) can enable the semi-hydrogenation of alkyne to alkene. In situ characterizations and theoretical simulations indicate that the geometric and electronic synergetic effects of Pd–Se NCs can facilitate the σ-π associative adsorption of CC bond in alkyne but suppress the over-hydrogenation of alkene. In particular, Pd4.5Se NCs exhibit high selectivity to the semi-hydrogenation of phenylacetylene (PA) to styrene (≥98.0 %) in the full conversion range, which has outperformed Pd NCs/C and commercial Lindlar catalyst. This work expands the mechanism understanding of Pd-based catalysts for selective hydrogenation, which may attract great interests of researchers in material science, chemistry, and catalysis.