Guanidinium-Based Ionic Liquids for High-Performance SO<sub>2</sub> Capture and Efficient Conversion for Cyclic Sulfite Esters
Zeyu Geng, Shuoyang Ma, Yuhang Li, Chao Peng, Binjian Jiang, Peilin Liu, Yun Xu
Abstract
Functionalized ionic liquids (ILs) show great potential in the application of fuel gas desulfurization. Herein, we report the synthesis and function of two new 1,1,3,3-tetramethylguanidine-based ILs (TMG-based ILs), 1,1,3,3-tetramethylguanidine methoxyacetate ([TMG][MOAc]) and 1,1,3,3-tetramethylguanidine ethoxyacetate ([TMG][EOAc]). As contrast, two traditional TMG-based ILs, 1,1,3,3-tetramethylguanidine tetrafluoroborate ([TMG][BF4]) and 1,1,3,3-tetramethylguanidine acetate ([TMG][Ac]) were synthesized. [TMG][EOAc] exhibited the highest SO2 capacity (10.33 mol·kg–1 ILs), during which the solubility of SO2 in the ILs was investigated with a reaction equilibrium thermodynamic model (RETM). Remarkably, the absorbed SO2 transformed into cyclic sulfite esters with high yields (up to 99%) in [TMG][MOAc] without a traditional desorption process. Thanks to its good stability, the cycloaddition reaction is fully revisable in [TMG][MOAc] in five cycling measurements. These coupled applications and molecular insights demonstrate a new type of functional material for SO2 capture and its value-added conversion and also provide a new strategy to deal with harmful gas in the most convenient way.