Guanidinium-Based Ionic Liquids for High-Performance SO2 Capture and Efficient Conversion for Cyclic Sulfite Esters

Aminoalkyl organosilicon with dual chemical sites for SO2 absorption and analysis of site-specific absorption entropy and enthalpy

Wet flue gas desulfurization is widely used for its high efficiency, however, the low absorption capacity, high viscosity and poor thermal stability of absorbents remains an open question. Herein, a low viscosity and high thermal stability SO2 absorbent with dual interacting sites was synthesized by introducing phenyl into organic silicon. The thermal stability of 1,5-bis (diethylamino)- 1,1,5,5-tetramethyl-3,3-diphenyltrisiloxane (BADPS) is comparable to ILs, while its viscosity is much lower than that of ILs. For the first time, we use a variant of the pseudo-first-order reaction rate equation obtained the reaction rate constant and the saturation absorption capacity. In addition, the optimal absorption and desorption temperatures were obtained based on an objective function. Mostly importantly, the absorption enthalpy change (ΔH) and entropy change (ΔS) of BADPS absorption reaction show the highest absolute values of SO2 absorbents reported so far. These results indicated that the prepared amine alkyl organosilicon could serve as a promising desulfurizing agent with low-energy consumption.

Cation functional group effect on SO2 absorption in amino acid ionic liquids

Introduction: The effect of the functional group of the cation on SO2 acidic gas absorption by some designed amino acid ionic liquids (AAILs) was studied. Methods: An isolated pair of glycinate anion and pristine imidazolium-based cation, as well as decorated cation functionalized by hydroxyl (OH), amine (NH₂), carboxylic acid (COOH), methoxy (OCH₃), and acetate (CH₃COO) groups, were structurally optimized by density functional theory (DFT) using split-valence triple-zeta Pople basis set. Results and Discussion: The binding and Gibbs free energy (ΔG_int) values of SO₂ absorption show the AAIL functionalized by the COOH group is the most thermodynamically favorable green solvent and this functional group experiences the closest distance between anion and captured SO₂ and vice versa in the case of cation … SO₂ which may be the main reason for being the best absorbent; in addition, the highest net charge-transfer amount of SO₂ is observed. Comparing the non-covalent interaction of the systems demonstrates that the strongest hydrogen bond between captured gas and anion, as well as π-hole, and van der Waals (vdW) interaction play critical roles in gas absorption; besides, the COOH functional group decreases the steric effect while the CH₃COO functional group significantly increases steric effect after absorption that declines the hydrogen bond.