Study on sulfur migration in activated carbon adsorption-desorption cycle: Effect of alkali/alkaline earth metals

摘要

Activated carbon(AC)has been widely used in the removal of SO_(2) from flue gas owing to its well-developed pore structure and abundant functional groups.Herein,the effect of alkali/alkaline earth metals on sulfur migration was investigated based on the dynamic adsorption and temperature programmed desorption experiment.The adsorption and desorption properties of six types of AC(three commercial and three laboratory-made)were carried out on a fixed-bed experimental device,and the physical and chemical properties of samples were determined by X-ray fluorescence,X-ray diffraction,scanning electron microscopy/energy dispersive X-ray,and X-ray photoelectron spectroscopy analysis.The experimental results showed that the adsorbed SO_(2) cannot be completely desorbed by increasing the regeneration temperature(350-850℃),while the SO_(2) fixed in the AC combines with the Ca-based minerals in the ash to form a stable sulfate.For different samples,higher ash content,higher CaO content in the ash and a more developed pore structure lead to a higher SO_(2) fixation rate.Moreover,the multiple adsorption-desorption cycles experiment showed that the effect of SO_(2) fixation is mainly reflected in the first cycle,after which the adsorption and desorption amount are approximately the same.This study elucidates the effect of alkali/alkaline earth metals on the adsorption-desorption cycle of AC,which provides a deeper understanding of sulfur migration in the AC flue gas desulfurization process.