Mesoporous silica nanospheres-encaged metal-metalloid alloy nanoparticles as efficient alkyne semi-hydrogenation catalysts

In this work, we report metal-metalloid Pd 2 B alloy nanoparticles as highly efficient and selective catalysts for semi-hydrogenations of alkynes . The mentioned materials feature the residence of small Pd 2 B nanoparticles in the cavities of hollow mesoporous silica nanospheres (Pd 2 B@HMSNs), and were synthesized by in situ transformation of Pd@HMSNs with B sources. At near room temperatures and atmospheric H 2 pressure, Pd 2 B@HMSNs exhibited high alkene selectivity for hydrogenations of a series of alkynes. Especially, such high alkene selectivity can be maintained with a prolonged reaction time, and nearly 100 % selectivity of cis to trans alkene is obtained for those internal alkynes. The excellent performance of Pd 2 B@HMSNs is originated from the residence of catalytic functionality inside hollow nanostructures and the change of electronic/geometric properties of surface Pd species by alloying with B, where the former improves their reusability and the latter suppresses the deep-hydrogenation of alkenes. • In situ solvothermal transformation of Pd with B sources could successfully synthesize Pd 2 B alloys. • Pd 2 B nanoparticles encaged in hollow silica nanospheres show greatly enhanced alkene selectivity for hydrogenation of alkynes. • The alkene selectivity for hydrogenation of alkynes over Pd 2 B was maintained with the significantly prolonged reaction time.