Crucial size effect on dicarbonylation of acetylene over Pd/CsHPMo heterogeneous catalysts

The structure-sensitive activity of Pd catalysts in carbonylation reactions is an urgent problem to be explored. Herein, Pd nanocrystals with uniform particle sizes (2.3 nm, 3.4 nm, 5.0 nm and 6.7 nm) were produced by using PVP to regulate the growth of Pd nanoparticles. The catalytic carbonylation reaction showed a "volcanic curve" with the increase in Pd particle size, and the obtained Pd/CsHPMo catalyst with 5 nm Pd nanoparticles was preferred. The 5.0Pd/CsHPMo catalyst, with the strongest "SMSI effect", shows the strongest Pd-CsHPMo interaction, and the generated electron-deficient Pd active sites accelerated the cycle of Pd^δ+ ↔ Pd (0), which endows its excellent catalytic efficiency. Meanwhile, DRIFTS in association with C₂H₂-TPD confirmed that the activation capacity of CO and C₂H₂ gas varies greatly on various Pd particle-size centers. These results provide a method for the accurate design of high-performance carbonylation catalysts.