Efficient Absorptive Oxidation of H2S Using a Fe(III)-Cu(II) Coupled DES (ChCl/EG) Desulfurizer

In this experiment, an EG/ChCl deep eutectic solvent (DES) was synthesized using choline chloride (ChCl) and ethylene glycol (EG) as the raw materials. The synthesized DES was characterized by Fourier transform infrared spectroscopy and thermogravimetric analysis. The results demonstrate the successful synthesis of DES. A certain amount of FeCl3 and CuSO4 was added to the DES to promote the absorption of H2S; thus, a Fe(III)-Cu(II) coupled DES desulfurization system was obtained. The effects of DES raw materials' ratio, FeCl3 concentration, water content, CuSO4 concentration, and reaction temperature on the desulfurization efficiency and the regeneration conditions were studied. The results show that ChCl/EG DES with a molar ratio of 1:2 has a better desulfurization effect, and the addition of an appropriate amount of water can effectively promote the dissolution of CuSO4 and the absorption of H2S. An appropriate increase in reaction temperature and CuSO4 concentration would also promote the absorption of H2S. When the concentration of CuSO4 in DES desulfurizer was 0.15 mol/L, the gas speed was 20 mL/min, and the sulfur capacity could reach 10.23 g/L. The desulfurizer could be regenerated by passing O-2, and the desulfurization efficiency did not change much after repeated use of desulfurization-regeneration many times. The desulfurization product was characterized by XRD as rhombohedral sulfur.