Synthesis of Guanidinium-Based Poly(ionic liquids) with Nonporosity for Highly Efficient SO2 Capture from Flue Gas

Because of considerable adsorption capacities of competitive gases N2 and CO2, many kinds of porous materials suffer from unsatisfied SO2/CO2 and SO2/N2 selectivities and thus hardly achieve deep removal of SO2 from flue gas. Herein, a novel type of guanidinium-based poly(ionic liquid) with the feature of nonporosity was designed and prepared through a facile copolymerization procedure. It is very attractive that nonporous guanidinium-based poly(ionic liquids) P([allyl-TMG]Br-DVB) by polymerization of (allyl-tetramethylguanidine)bromide with divinylbenzene had almost excluded the adsorption of N2 (0.01 mmol g–1) and CO2 (0.07 mmol g–1) but showed very high SO2 capacity (9.79 mmol g–1) at 25 °C and 1 bar. The high selectivities of SO2/CO2 (452) and SO2/N2 (2294) were accordingly obtained. Furthermore, column breakthrough experiments confirmed the excellent separation performance of P([allyl-TMG]Br-DVB) in deeply eliminating 2000 ppm SO2 in the mixture of SO2/N2/CO2. The employment of nonporous poly(ionic liquids) as efficient adsorbents is an effective strategy for the deep removal of SO2 from flue gas.