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

Wen, Yaoshun, Wang, Gang, Wang, Qian, Xu, Chunming, Gao, Jinsen
Industrial & Engineering Chemistry Research 2012 v.51 no.10 pp. 3939-3950
X-ray diffraction, adsorbents, adsorption, atmospheric pressure, chemical reactions, desulfurization, energy-dispersive X-ray analysis, engineering, gasoline, models, nitrogen, oxygen, physicochemical properties, temperature, zinc sulfate
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 N₂ isotherms were used to identify changes in the physical and chemical properties of the adsorbent before and after regeneration. The results showed that high O₂ 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 O₂ 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.