Alloyed PdCu Nanoparticles within Siliceous Zeolite Crystals for Catalytic Semihydrogenation.

Selective hydrogenation of acetylene to ethylene is an industrially important process to purify the raw ethylene stream for producing high-grade polyethylene. The supported Pd catalyst exhibits superior activity for acetylene hydrogenation but suffers from poor ethylene selectivity because of the easy overhydrogenation to produce ethane. Here, we report that the PdCu alloy nanoparticles within siliceous zeolite crystals effectively tuned Pd-catalyzed overhydrogenation into semihydrogenation. This catalyst displayed an ethylene selectivity of 92.9% with a full conversion of acetylene. Mechanism studies reveal that the zeolite fixation stabilized the alloyed structure, where the electron-enriched Pd surface benefits the rapid ethylene desorption to hinder the deep hydrogenation. This work provides an efficient strategy for a rational design of bimetallic metal catalysts for selective hydrogenations.