Facile synthesis of N-doped graphene encapsulated Ni@N/C catalyst and its catalysis for highly selective semi-hydrogenation of alkynes

Abstract

Although precious transition metals such as palladium, platinum, and iridium are widely used in hydrogenation reactions, the earth-abundant transition metal-catalyzed highly selective semi-hydrogenation of terminal alkynes to terminal alkenes remains poorly developed and a challenge. Herein we demonstrate the excellent selective, cost-effective semi-hydrogenation of terminal alkynes via a novel graphene encapsulated Ni@N/C catalyst. The graphene layer encapsulated nano-catalyst Ni@N/C could significantly avoid metal leaching and improve the stability of the catalyst. The strong interaction of nitrogen with the Ni nanoparticles regulates the activity of Ni towards selective semi-hydrogenation of terminal alkynes. Substrates having un-functionalized as well as functionalized substituents, and substrates having sensitive functional groups (olefins, ketones) which pose a challenge to hydrogenate, were semi-hydrogenated with excellent conversion (up to 99%) and selectivity (up to 99%) under optimized reaction conditions.