Abstract:

This study employed an impregnation method to prepare a series of ZnNi/Al₂O₃ catalysts with varying Zn content. The catalysts were characterized using techniques such as X-ray powder diffraction （XRD）， hydrogen temperature-programmed reduction （H₂-TPR）， X-ray photoelectron spectroscopy （XPS）， and density functional theory （DFT） calculations. The structural and property characterization aimed to investigate the impact of Zn introduction on the catalysts during the phenylacetylene selective hydrogenation to styrene. Experimental results revealed a significant enhancement in catalyst performance with the introduction of Zn， leading to an increase in the conversion rate of phenylacetylene selective hydrogenation to styrene from 92.2% to 96.8%. Characterization of the support and catalyst structure indicated that Zn doping into the NiO lattice substantially strengthened the interaction between the active metal Ni and the support， significantly improving Ni dispersion. Due to the facile segregation of Zn metal， the ZnNi alloy formed on the reduced catalyst surface altered the surface electronic structure of Ni metal. The migration of Zn surface electrons to Ni formed electron-rich Ni active centers， facilitating the phenylacetylene selective hydrogenation to styrene. Theoretical calculations indicated that the introduced Zn led to the formation of a stable Zn₇Ni structure on the catalyst surface， resulting in a transition hydrogenation barrier for styrene of 1.42 eV， significantly higher than the desorption barrier for styrene in selective hydrogenation （0.55 eV）. These findings elucidate the fundamental factors underlying the performance enhancement of Ni/Al₂O₃ catalysts by the Zn component.

Key words: Phenylacetylene selective hydrogenation, Zinc modification, Nickel-based catalyst, Theoretical simulation