Tailoring the Pore Size and Chemistry of Ionic Ultramicroporous Polymers for Trace Sulfur Dioxide Capture with High Capacity and Selectivity

Here we demonstrate the deep removal of SO2 with high uptake capacity (1.55 mmol g(-1)) and record SO2/CO2 selectivity (>5000) at ultra-low pressure of 0.002 bar, using ionic ultramicroporous polymers (IUPs) with high density of basic anions. The successful construction of uniform ultramicropores via polymerizing ionic monomers into IUPs enables the fully exploitation of the selective anionic sites. Notably, the aperture size and surface chemistry of IUPs can be finely tuned by adjusting the branched structure of ionic monomers, which play critical roles in excluding CH4 and N-2, as well as reducing the coadsorption of CO2. The swelling property of IUPs with adsorption of SO2 contributed to the high SO2 uptake capacity and high separation selectivity. Systematic investigations including static gas adsorption, dynamic breakthrough experiments, stability tests and modeling studies confirmed the efficient performance of IUPs for trace SO2 capture.

Automated summary

The study demonstrates the deep removal of SO2 at ultra-low pressure using ionic ultramicroporous polymers with high uptake capacity and selectivity. The construction of uniform ultramicropores via polymerizing ionic monomers allows for full utilization of selective anionic sites. The tuned aperture size and surface chemistry of IUPs play a critical role in excluding unwanted gases and improving separation selectivity.