Microwave-synthesized heteroaromatic porous organic polymers for CO₂ capture and hydrogen storage

In this paper, three porous organic polymers (POPs) were synthesized by microwave-assisted Friedel-Crafts polymerization reaction of 1,3,5-tris(2-thienyl)benzene (TTB) with furan (HAF), thiophene (HAT), and pyrrole (HAP) in the presence of dimethoxymethane using anhydrous iron (III) chloride as a catalyst. The polymers displayed inherent porosity, with BET surface areas ranging from 528 to 634 m²/g. These polymers exhibited high CO₂ adsorption capacity, with values of 2.61, 2.17, and 2.37 mmol/g at 273 K and 1 atm, as well as strong affinity, with Q_st values of 43–48 kJ/mol. The polymers showed hydrogen storage of 3.3–5.3 mmol/g (0.66–1.06 wt%) at 77 K, and 1 atm. The polymers showed Initial slope selectivity for CO₂/N₂: 34–61 at 273 K and 1 atm, and 23–57 at 298 K and 1 atm. Whereas, the polymers showed initial slope selectivity for CO₂/CH₄: 5–9 at 273 K and 4–7 at 298 K and 1 atm. Besides, the HAP at 273 K and HAF at 298 K showed highest IAST selectivity values of 231.18 and 257.49, respectively. Grand Canonical Monte Carlo (GCMC) simulations revealed that the polymers exhibit matching electronic properties with CO₂ molecules and achieve excellent selectivity in accordance with the hard-soft acid-base (HSAB) theory. These findings demonstrate the potential of these polymers for CO₂ capture and clean energy applications.