Regeneration performance and characteristic of iron oxide/arenaceous sorbents in the atmosphere of O2/N2

Abstract

The performance and the change characteristic of iron oxide/arenaceous sorbent in the regeneration reaction are systematically investigated by studying the effects of temperature, space velocity and O2 concentration on the sorbent in a fixed-bed quartz reactor. Sulfidation-regeneration cycles were also conducted to evaluate the reusability of the sorbents. The surface and bulk structural features of the sorbents, both before and after regeneration, were characterized by X-ray diffraction, X-ray photoelectron spectroscopy, scanning electron microscope, energy dispersive spectroscopy, Fourier transform infrared spectroscopy and N2 adsorption-desorption. The results show that the sorbents exhibit the highest regeneration rate at the conditions of 6vol.% O2, 650°C, and space velocity of 3000h−1. After five sulfidation-regeneration cycles, the breakthrough curves of regenerated sorbents changed slightly and the regeneration rates of the regenerated sorbents still exceeded 95%. The characterization data indicates that the outer layer electron density of surface atoms decreased in the regeneration process, which adversely affects the adsorption rate of acidic H2S and the reaction rate of H2S with Fe2O3 on the surface of sorbents. It can be seen from XRD analysis that the particle size of the sorbent gradually increased as the number of sulfidation-regeneration cycles increased, leading to reduced surface area and blocked pore structure. Furthermore, the internal structure deteriorated due to sintering, which resulted in the lowered sulfidation performance of the regenerated sorbent.