Mechanistic and Atomic-Level Insights into Semihydrogenation Catalysis to Light Olefins

Semihydrogenations of alkynes and alkadienes to light olefins catalyzed by a heterogeneous catalyst are widely applied in the chemical industry, but it remains challenging to design high-performance catalysts for these processes. The well-developed synthesis methodologies, characterization techniques for catalyst structures, and theoretical calculations in recent decades render opportunities for understanding mechanisms and elaborating the structures of active sites at the atomic level. This Review summarizes recent advances in the mechanistic and atomic-level insights into semihydrogenation catalysis for alkynes and alkadienes to light olefins. The structure-sensitivity, information on active sites, and reaction kinetics are initially discussed to demonstrate the knowledge on the mechanistic and kinetics details of the hydrogenations of alkynes and alkadienes. We then introduce the regulations for the active sites, especially at the atomic level, based on three categories, i.e., site-isolation, local environment regulation, and oxygen vacancy and interfacial sites. Followed by the discussion on the conventional thermocatalytic hydrogenations, the emerging photocatalytic and electrocatalytic semihydrogenations of alkynes and alkadienes are further covered. Finally, we provide a brief overview on the current status of this field and a perspective for future study on the atomic-level design and regulation of catalysts for controlling the selectivity to target products.