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 in situ 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.