Electron-deficient Pd nanoparticles on nitrogen-doped carbon nanofibers for high selectivity alkyne transfer semi-hydrogenation

Abstract

Improving the alkyne hydrogenation activity and selectivity of Pd catalysts is of great significance through structural design and surface electron regulation. In this study, electron-deficient Pd nanoparticles on mesoporous nitrogen-doped carbon nanofibers were produced through a ZIF-8 template assisted electrospinning method, which exhibited high selectivity for transfer hydrogenation of phenylacetylene (PA) by using ammonia borane (AB) as the hydrogen source. The porous carbon nanofiber carriers not only facilitate the uniform dispersion and anchoring of Pd nanoparticles but also provide confined space that promotes the transfer hydrogenation. The electron-deficient Pd nanoparticles decrease the desorption energy of styrene (ST), enhancing its dissociation from the reaction site and improving the selectivity of ST. They achieved 98% ST selectivity at nearly 100% PA conversion and maintained high selectivity above 96% over prolonged reaction time and at a high AB/PA feed ratio. Moreover, the carbon nanofiber substrate allows for convenient and complete recovery from the reaction system without a significant decrease in conversion and selectivity, indicating its excellent structural and performance stability. It also exhibited high selectivity (>93%) in the semi-hydrogenation of various other aromatic alkynes. This work provides a valuable reference for designing high efficiency transfer semi-hydrogenation catalysts.