Trail of sulfur during the desulfurization via reactive adsorption on Ni/ZnO

The reactive adsorption behavior of thiophene on the reduced Ni/ZnO sample was investigated by a combination of theoretical and experimental study. It is widely accepted that Ni is responsible for the sulfur-removal of thiophene to release S-free hydrocarbons. Such surface reaction was simulated by DFT method. It is demonstrated that thiophene is mainly adsorbed as π-complexation mode over metallic Ni. During desulfurization, the SNi bond is formed and the CS bond is thus split without pre-hydrogenation, resulting in the formation of Ni3S2 phase and S-free C4 olefin which can be further saturated in the presence of H2. The S-transfer between Ni3S2 and ZnO was monitored by in-situ XRD and STEM with EDS mapping. Two essential features were identified for efficient S-transfer, namely, 1) the H2 atmosphere, and 2) the two phases are presented with close contact. Based on the acquired information, a general scenario of sulfur trail has been proposed for the desulfurization of thiophene on Ni/ZnO.