Regeneration characteristics and kinetics of Fe2O3/lignite semi-coke hot gas desulfurizer at O2/N2 atmosphere

Abstract

The Fe2O3/lignite semi-coke sorbent was prepared by co-precipitation method with assistance of ultrasonic irradiation and underwent 4 sulfidation–regeneration cycles with O2/N2 as regeneration gases. The fresh, sulfided, and regenerated sorbents were characterized using XRD, SEM, XPS, and BET technologies in this paper. The regeneration mechanism was also discussed. It was found that in the oxygen atmosphere, FeS in the sulfided sorbent reacted with oxygen to produce Fe2O3 and SO2, the sulfate formed in regeneration process is easy to decompose at higher temperature. Regeneration kinetic studies were also performed at regeneration temperatures of 625–700 °C. It was found that the reaction order of regeneration with respect to O2 is first order. The equivalent grain model can be effectively used to correlate with the experimental data. In the early stage of reaction (x 70 %). According to the model, the apparent activation energy and the corresponding frequency factor for two different stages are 14.73 kJ mol−1 and 4.43 × 10−2 m s−1, 31.32 kJ mol−1 and 5.77 × 10−4 m2 s−1, respectively.