Investigation of Sn Promoter on Ni/CeO₂ Catalysts for Enhanced Acetylene Semihydrogenation to Ethylene

Ethylene, as an important chemical raw material, could be produced through the coal-based acetylene hydrogenation route. Nickel-based catalysts demonstrate significant activity in the semihydrogenation reaction of acetylene, but they encounter challenges related to catalyst deactivation and overhydrogenation. Herein, the effect of Sn promoter on Ni/CeO₂ catalysts has been comprehensively explored for acetylene semihydrogenation. The optimized Ni/8%Sn-CeO₂ catalytic performance was significantly improved, with 100% acetylene conversion and 82.5% ethylene selectivity at 250 °C, and the catalyst maintained high catalyst performance within a 1000 min stability test. A series of characterization tests show that CeO₂ modified by moderate Sn⁴⁺ doping is more conducive to modulating the charge structure and geometry of the Ni active center. Additionally, the <i>in situ</i> Diffuse Reflectance Infrared Fourier Transform Spectroscopy and density functional theory results indicated that catalysts doped with Sn⁴⁺ facilitated more efficient desorption of ethylene from the catalyst surface compared to Ni/CeO₂ catalysts, thus improving ethylene selectivity and yield. This study highlights an effective strategy for improving the catalytic performance of rare-earth-based catalysts through the incorporation of effective metal promoters.