• DOI:10.1039/c7dt04726f
• Corpus ID: 3504354

The reaction mechanism and selectivity of acetylene hydrogenation over Ni-Ga intermetallic compound catalysts: a density functional theory study.

@article{Rao2018TheRM,
  title={The reaction mechanism and selectivity of acetylene hydrogenation over Ni-Ga intermetallic compound catalysts: a density functional theory study.},
  author={Deming Rao and Shitong Zhang and Changming Li and Yudi Chen and Min Pu and Hong Yan and Min Wei},
  journal={Dalton transactions},
  year={2018},
  volume={47 12},
  pages={
          4198-4208
        }
}

• Deming Rao, Shitong Zhang, +4 authors Min Wei
• Published 20 March 2018
• Chemistry
• Dalton transactions

Intermetallic compounds (IMCs) have shown excellent catalytic performance toward the selective hydrogenation of acetylene, but the theoretical understanding on this reaction over Ni-based IMCs is rather limited. In this work, the adsorptions of the C2 species, Bader charge, projected density of states (PDOS) and the reaction pathways were calculated by the density functional theory (DFT) method to investigate the mechanism and selectivity for the acetylene hydrogenation on the (111) surface of NinGa (n = 1, 3) IMCs, with a comparative study on the pristine Ni(111) surface. The results indicate that the adsorption energy of acetylene increased along with the Ni/Ga ratio, therefore a feasible acetylene adsorption on the Ga-rich surface guaranteed a low effective barrier, leading to the best activity for the NiGa(111) surface among three surfaces. Bader charge analysis shows that electrons transferred from Ga atoms to Ni atoms and further delivered to C2 species, decreasing the adsorption capacity of C2 species on NiGa(111) in comparison with those on Ni(111) and Ni3Ga(111). The reaction pathway of acetylene hydrogenation to ethylene via vinyl or even over-hydrogenation to ethane via ethyl is more favorable than the pathway involving the ethylidene intermediate on all surfaces. Moreover, the ethylene selectivity has a positive correlation with the gallium content by comparing the desorption barrier with the hydrogenation barrier of ethylene, thus the NiGa(111) surface also exhibits the best selectivity. Therefore, the NiGa(111) surface demonstrates to be an excellent reaction facet for the semihydrogenation of acetylene, which agreed with the experimental findings, and would provide helpful instructions for designing and preparing highly-selective and noble-substitute catalysts of alkyne semihydrogenation.