文摘
High-temperature gas desulfurization is an efficient and environmentally friendly process for syngas cleanup. The present study investigated the in situ preparation of a zinc oxide/red clay desulfurization sorbent and its desulfurization–regeneration behavior in O2/N2 atmospheres. The effects of regeneration temperature, space velocity, and O2 concentration on the regeneration behaviors of ZnO/red clay sorbents were also investigated. The surface and structural properties of the sorbents before and after regeneration were characterized by thermogravimetric–differential scanning calorimetry, X-ray diffraction, X-ray photoelectron spectroscopy, scanning electron microscopy, elemental mapping, and N2 adsorption–desorption analyses. According to the results, the highest regeneration rate was achieved under the conditions of 6 vol % O2 and a space velocity of 3000 h–1 at 650 °C. After four cycles of desulfurization–regeneration experiments, the breakthrough time of the regenerated sorbents reduced by 18.7% and some breakages and cracks were also observed in the regenerated sorbents, although there was only a slight change in their mechanical strength. The characterization data indicate that the number of surface Zn atoms decreased in the regeneration process, which adversely affects the sorbent’s adsorption efficiency for acidic H2S. After regeneration, the results of N2 adsorption and SEM indicated the deteriorated structure of the sorbent. In addition, the XPS and XRD results indicated the presence of sulfur-containing compounds which also contributed to the lowered desulfurization activity of the sorbent.
