Breaking the activity-selectivity trade-off for acetylene semihydrogenation by Pd2 dual-atom site

Acetylene semihydrogenation is a critical process in the polyolefin industry by selectively removing trace acetylene from ethylene-rich reformate. However, this reaction is generally limited by the inherent activity-selectivity trade-off due to the thermodynamic advantage of overhydrogenation. Herein, we develop a facile and straightforward strategy to construct Pd 2 dual-atom sites anchored on defect-rich surface-graphitized nanodiamond (ND@G) via the solvent-mediated dispersion of palladium carboxylate driven by the chelation of palladium precursors via carboxylate anion. Cs-corrected HAADF-STEM images coupled with XAS analysis unambiguously manifest the successful architecting of Pd 2 dual-atom sites. Compared to Pd 1 single-atom sites, the obtained Pd 2 /ND@G sample demonstrates superior catalytic performance in acetylene semihydrogenation, with the corresponding TOF values increased from 0.151 s −1 to 1.953 s −1 , without the obvious decline of ethylene selectivity (93.2%, at full acetylene conversion). C 2 H 2 /C 2 H 4 -TPD, H 2 -D 2 exchange reaction, isotope-labeled TPSR combined with DFT calculations confirm the effective co-activation of C 2 H 2 /H 2 on Pd 2 dual-atom sites while maintaining the weak adsorption of ethylene similar to that on its single-atom sites, which can break the activity-selectivity trade-off in acetylene semihydrogenation.