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 H2 attacks C4H4S–adsorbent system, activation of the Csingle bondS bonds occurs. When the second H2 continues to attack the adsorption configuration, the Csingle bondS bonds are cracked. In the process, H2 plays an important role in the cleavage of the Csingle bondS 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 H2 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.