Selective Hydrogenation of Acetylene to Ethylene over Bimetallic Catalysts

Ni/alpha-Al2O3 catalyst and a series of bimetallic catalysts including Pd-Ag, Ni-Pd, Ni-Zn, Ni-Ag, and Ni-Ga were synthesized, characterized, and tested in selective hydrogenation of acetylene to ethylene. The bimetallic catalyst Ni-Ga exhibited almost the same ethylene selectivity compared to Pd-Ag based catalyst. The effect of the Ni/Ga ratio on the catalytic activity and selectivity to ethylene in acetylene hydrogenation was evaluated. Characterization by transmission electron microscopy, X-ray diffraction, hydrogen temperature-programmed reduction, and X-ray photoelectron spectroscopy was carried out to identify active phases on Ni-Ga based catalysts, which was correlated with catalytic performance and the reaction mechanism occurring over the catalyst. The presence of Ga in Ni-Ga lattice structure confined the movement of dissociated H* and reduced the adsorption binding energy of ethylene, which could prevent overhydrogenation of acetylene.