Mesoporosity‐Enabled Selectivity of Mesoporous Palladium‐Based Nanocrystals Catalysts in Semihydrogenation of Alkynes

We reported mesoporosity engineering as a general strategy to promote semihydrogenation selectivity of palladium (Pd)‐based nanobundles catalysts. The best mesoporous PdP displayed full conversion, remarkable activity, excellent selectivity, and high stability in semihydrogenation of 1‐phenyl‐1‐propyne, all of which are remarkably better than commercial Lindlar catalysts. Mechanistic investigations ascribed high semihydrogenation selectivity to the continuous crystalline framework and penetrated mesoporous channel of catalysts that weakened the adsorption and interaction capacity of alkenes and thus inhibited over‐hydrogenation of alkenes to industrially unfavorable alkanes. Density functional theory calculations further demonstrated that convex crystalline mesoporosity of nanobundles catalysts electronically optimized the coordination environment of Pd active sites and energetically changed hydrogenation trends, resulting in a superior semihydrogenation selectivity to targeted alkenes. Mesoporosity engineering is demonstrated as an efficient route for boosting catalytic selectivity of Pd‐based nanobundle catalysts in the semihydrogenation of alkynes. Mechanistic studies reveal that the continuous crystalline framework and penetrated mesoporous channel of mesoporous Pd‐based catalysts synergistically weaken the adsorption and binding strength of alkenes and energetically disable further over‐hydrogenation of alkenes to alkanes.