Study on the Desulfurization and Regeneration Performance of Functional Deep Eutectic Solvents.

Four deep eutectic solvents (DESs) were synthesized, and 5-30% polyethylenimine (PEI) was added to make functional DESs (FDESs) for dynamic absorption experiments of hydrogen sulfide. The synthesized FDESs were characterized by Fourier transform infrared spectroscopy, thermogravimetric analysis, and nuclear magnetic resonance. The results demonstrated the successful synthesis of FDESs. The interaction between HS and the FDESs was discussed at a molecular level via the quantum chemical calculations. It was noticed that FDESs prefer chemisorption on HS. In this work, the 25% PEI/FDES@EG showed the highest desulfurization performance. The effects of HS concentration and temperature on the desulfurization performance were investigated. It was found that a relatively low temperature (30 °C) was favorable for the absorption of HS. The 25% PEI/FDES@EG could remove HS efficiently over a low HS concentration. Moisture played an important role in the FDES desulfurization system. The absorption/desorption cycle experiment indicated that the FDESs retain their good regeneration performance for at least five times.