Desulfurization performance and kinetics of potassium hydroxide-impregnated char sorbents for SO2 removal from simulated flue gas

Potassium hydroxide-impregnated char sorbents (KOH/char) prepared via an ultrasonic-assisted method were used for SO₂ removal from flue gas. The desulfurization experiment was analyzed using a fixed-bed reactor under 40-150 ℃ temperature range, using simulated flue gas. X-ray diffraction (XRD), Fourier-transform infrared spectroscopy, and scanning electron microscopy/energy-dispersive X-ray spectroscopy (SEM/EDS) were used to analyze both the chemical and physical characteristics of the sorbents. The analyzed results exposed that the complete elimination of SO₂ from flue gas was achieved when using the char/KOH sorbent with a mass ratio of char to KOH of 11:1. It was noted that temperature had a substantial influence on the desulfurization performance with sulfur capacity maximized at 100 ℃. Experimental results also revealed that a small amount of O₂ present in the solvent could improve the SO₂ removal efficiency of the sorbent. The analyzed XRD patterns showed that K₂SO₄ was the main desulfurization product, which was consistent with the SEM/EDS analysis. The experimental results were well-described with the Lagergren first-order adsorption kinetics model with the activation energy (E_a) of the SO₂ adsorption by KOH/char sorbent of 20.25 kJ/mol.