Isoprene selective hydrogenation using AgCu-promoted Pd nanoalloys

Alloying is an effective approach to improve the catalysis performance of Pd-based catalysts for the selective hydrogenation of diolefins towards monoolefines. Herein, PdAgCu ternary nanoalloy catalysts were synthesised by a stepwise impregnation method for isoprene selective hydrogenation. The addition of a moderate amount of Ag and Cu to Pd significantly enhances the isoamylene selectivity in the isoprene hydrogenation, and decreases the non-desired over-hydrogenation. In addition, the loading molar ratio of PdAgCu with 3 : 2 : 3 as the optimal ternary nanoalloy composition maximizes the isoprene conversion (98%) and the monoolefins yield (92%). The surface structure of the catalyst was probed using H₂-TPR, TEM, XRD, and XPS characterization methods, and it was confirmed that the surface Pd composition ratio between the metallic and oxidized states shows significant effects on the monoolefines yield. This work demonstrates the advantages of PdAgCu ternary nanoalloy catalysts for isoprene selective hydrogenation, which also provides guidelines for the development of other Pd-based ternary nanoalloys for diolefins selective hydrogenation.