Molecular insights into the absorption of SO2 with amine alkyl organosilicon and its optimal absorption temperature

The high viscosity of ionic liquids (ILs) and the poor thermal stability of deep eutectic solvents (DESs) limit their application in the real industry of SO2 removal. Amine alkyl organosilicon can be considered as a potential candidate owing to its excellent physicochemical properties, desulfurization performance, and low regeneration sensible heat. In this work, an amine alkyl organosilicon, namely N-butyl-N-((methyldiphenylsilyl)methyl) butan-1-amine (BMMBA), characterized by low viscosity and high thermal stability, was innovatively synthesized. Dynamic absorption experiments show that BMMBA exhibits high SO2 absorption capacity and excellent SO2/CO2 selectivity. In addition, the absorption mechanism was revealed by quantum chemical (QC) calculation and molecular dynamics (MD) simulations. The consistency between experiments and theoretical calculation indicates that SO2 interacts mainly with the N atom and benzene group of BMMBA. Further, thermodynamic analysis reveals that BMMBA displays exceptionally steep gradient of absorption capacity curves with temperature variations, which arise from an extremely negative absorption entropy change (ΔS), favoring the reduction of regeneration sensible heat energy consumption. Ultimately, the optimization results suggest that the BMMBA system has a lower sensible heat of regeneration compared to conventional absorbents. The novel absorbent and investigate conclusions demonstrated herein could provide a theoretical basis for designing highly effective SO2 absorbents.