The use of fossil fuels for energy production is accompanied by carbon dioxide release into the environment causing catastrophic climate changes. Meanwhile, replacing fossil fuels with carbon-free nuclear energy has the potential to release radioactive iodine during nuclear waste processing and in case of a nuclear accident. Therefore, developing efficient adsorbents for carbon dioxide and iodine capture is of great importance. Two nitrogen-rich porous polymers (NRPPs) derived from 4-bis-(2,4-diamino-1,3,5-triazine)-benzene building block were prepared and tested for use in CO and I capture. Copolymerization of 1,4-bis-(2,4-diamino-1,3,5-triazine)-benzene with terephthalaldehyde and 1,3,5-tris(4-formylphenyl)benzene in dimethyl sulfoxide at 180 °C afforded highly porous NRPP-1 (SA = 1579 m g) and NRPP-2 (SA = 1028 m g), respectively. The combination of high nitrogen content, π-electron conjugated structure, and microporosity makes NRPPs very effective in CO uptake and I capture. NRPPs exhibit high CO uptakes (NRPP-1, 6.1 mmol g and NRPP-2, 7.06 mmol g) at 273 K and 1.0 bar. The 7.06 mmol g CO uptake by NRPP-2 is the second highest value reported to date for porous organic polymers. According to vapor iodine uptake studies, the polymers display high capacity and rapid reversible uptake release for I (NRPP-1, 192 wt % and NRPP-2, 222 wt %). Our studies show that the green nature (metal-free) of NRPPs and their effective capture of CO and I make this class of porous materials promising for environmental remediation.

Development of efficient sorbents for carbon dioxide (CO) capture from flue gas or its removal from natural gas and landfill gas is very important for environmental protection. A new series of heteroatom-doped porous carbon was synthesized directly from pyrazole/KOH by thermolysis. The resulting pyrazole-derived carbons (PYDCs) are highly doped with nitrogen (14.9-15.5 wt %) as a result of the high nitrogen-to-carbon ratio in pyrazole (43 wt %) and also have a high oxygen content (16.4-18.4 wt %). PYDCs have a high surface area (SA = 1266-2013 m g), high CO Q (33.2-37.1 kJ mol), and a combination of mesoporous and microporous pores. PYDCs exhibit significantly high CO uptakes that reach 2.15 and 6.06 mmol g at 0.15 and 1 bar, respectively, at 298 K. At 273 K, the CO uptake improves to 3.7 and 8.59 mmol g at 0.15 and 1 bar, respectively. The reported porous carbons also show significantly high adsorption selectivity for CO/N (128) and CO/CH (13.4) according to ideal adsorbed solution theory calculations at 298 K. Gas breakthrough studies of CO/N (10:90) at 298 K showed that PYDCs display excellent separation properties. The ability to tailor the physical properties of PYDCs as well as their chemical composition provides an effective strategy for designing efficient CO sorbents.

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