Guanidinium‐based dicarboxylic acid ionic liquids for SO₂ capture

Abstract

BACKGROUND Ionic liquids (ILs) have been widely used in the field of SO2 separation for gases. In this study, two kinds of guanidinium‐based dicarboxylic acid ionic liquids including [1,1,3,3‐tetramethylguanidinium][Poly(ethylene glycol) bis(carboxymethyl) ether] ([TMG][PBE]) and [1,1,3,3‐tetramethylguanidinium] [Suberic acid] ([TMG][SUB]) were synthesized, and their absorption and desorption performance of SO2 were investigated. RESULTS The saturated molar ratio of SO2 to [TMG][PBE] and [TMG][SUB] were 8.74 and 5.96 mol SO2 per mole ILs at 25 °C, respectively. [TMG][PBE] saturated with SO2 was easier to desorb and could be recycled at least 5 times without loss of initial performance, while the ability to absorb SO2 by [TMG][SUB] was gradually weakened after desorption. The absorption mechanism is discussed. Results showed that SO2 could interact not only with the amino group on the cation but also with the methylene bonded to the carbonyl carbon on the anion for [TMG][SUB]. As for [TMG][PBE], SO2 could interact with the ether group by S‐O ligand interaction, instead of interacting with the methylene group bonded to the carbonyl carbon on the anion. [TMG][PBE] show good performance for SO2 capture. CONCLUSION The anion of dicarboxylic acid‐based ILs plays an important role in absorption/desorption of SO2 on the basis of the experimental results. © 2016 Society of Chemical Industry

Highly efficient and reversible absorption of SO2 by hydroxyl ammonium ionic liquids at low partial pressure

“…When the temperature increased from 25 °C to 60 °C, the molar absorption capacities of SO 2 decreased by about 30.9%, 37.8% and 37.3% for [TEOA][CA], [TEOA][LA] and [TEOA][AC], respectively. The effect of temperature on absorption of SO 2 could be explained on the basis of exothermic reactions between ILs and SO 2 molecules . Released heat could increase the temperature of ILs rapidly when the thermostat was turned off, as shown in Fig.…”

“…The effect of temperature on absorption of SO 2 could be explained on the basis of exothermic reactions between ILs and SO 2 molecules. 14,[33][34][35][36] Released heat could increase the temperature of ILs rapidly when the thermostat was turned off, as shown in Fig. S2.…”

“…Huang et al and Rasmussen et al reported five kinds of TMG‐based ILs, which could remove SO2 in high molar ratios . More recently, Meng et al synthesized a novel ether functionalized IL ([TMG] 2 [PBE]), which could absorb 8.74 molSO 2 /molIL at 101 kPa and 298 K. [TMG] 2 [PBE] could be recycled at least five times without loss of initial performance. However, poor thermal stability of some TMG‐based ILs limited their further industrial applications …”

“…This value was much higher than those of the other hydroxyl ammonium ILs, guanidinium based ILs11,29,33 and azole based ILs18,32,34 at low SO 2 partial pressure. However, the absorption capacity of[TEOA][CA] at low SO 2 partial pressure was lower than those for some ILs with pure SO 2 , such as [TMG]2 [PBE] (8.74 mol/mol)14 and E 3 [Tetz] (4.43 mol/mol) 20.…”

Solubility of sulfur dioxide in tetraglyme-NH4SCN ionic liquid: high absorption efficiency

“…26 In order to improve the absorption capacity of ionic liquids, researchers prepared a variety of functional ionic liquids. There are two main types of functional ionic liquids, including ether functional ionic liquids [27][28][29][30][31] and amine functional ionic liquids. [32][33][34] The latter generally has poor selectivity and desorption ability due to its chemical interaction with SO 2 .…”