Mechanistic investigations on the adsorption of thiophene over Zn3NiO4 bimetallic oxide cluster

Desulfurization mechanism of thiophene was studied via reactive adsorption over a Zn3NiO4 cluster by density functional theory calculations. A gas-phase thiophene molecule is adsorbed on the Ni site instead of Zn site in the Zn3NiO4 adsorbent. When the first H-2 attacks C4H4S-adsorbent system, activation of the C-S bonds occurs. When the second H-2 continues to attack the adsorption configuration, the C-S bonds are cracked. In the process, H-2 plays an important role in the cleavage of the C-S bonds of organic sulfur compound. The remaining S species on the Ni site of Zn3NiO4 adsorbent are dealt with two pathways. One is that nickel sulfide is reduced in the presence of H-2 to form H2S with an energy barrier of 0.859 eV, and then the active nickel species is liberated from nickel sulfide in the S-adsorbent system. The other is that sulfur can be directly transferred from Ni site to Zn site in the adsorbent with a smaller energy barrier of 0.634 eV. Thus, in a reaction adsorption desulfurization, it favors the process that sulfur is directly transferred from Ni site to Zn site. (c) 2012 Elsevier B.V. All rights reserved.