Regeneration Characteristics and Kinetics of Ni/ZnO-SiO2-Al2O3 Adsorbent for Reactive Adsorption Desulfurization

Regeneration experiments on Ni/ZnO-SiO2-Al2O3 adsorbents for gasoline reactive adsorption desulfurization (RADS) were carried out in a fixed-bed microreactor at atmosphere pressure. X-ray diffraction, scanning electron microscopy/energy-dispersive spectroscopy, X-ray photoelectron spectrometry, and N-2 isotherms were used to identify changes in the physical and chemical properties of the adsorbent before and after regeneration. The results showed that high O-2 concentrations significantly increase the regeneration rate of the adsorbent but yield zinc sulfate. A regeneration condition that decreases the formation of zinc sulfate, including low O-2 concentration with high temperature, was then investigated. Finally, a shrinking core model (SCM) was applied to account for the regeneration kinetics of the Ni/ZnO-SiO2-Al2O3 adsorbent, and the relevant kinetic parameters were determined. The regeneration is controlled first by a chemical reaction and then by layer diffusion. The desulfurization activity of the regenerated adsorbent over three desulfurization and regeneration cycles is almost identical to that of fresh adsorbent.