A cross-linked hybrid poly Schiff-base (PSB) was synthesized and characterized through spectroscopic, morphological, and structural approaches. The BET surface area (SBET) of the PSB is 20.33 m2/g, the pore volume (Vp) is 0.024 cm3/g, and the pore diameter (Dp) is 4.13 nm. The current study elucidates PSB’s strong chemical and thermal stability, as well as the remarkable capacity to adsorb CO2 with perfect selectivity. This property is accomplished by the synergistic interaction of the polymer’s physicochemical and structural features when exposed to CO2, N2 and CH4 molecules. This mesoporous polymer exhibits a CO2/N2 = 60 and CO2/CH4 = 10.5 selectivity, and can adsorb 3.22 mmol/g CO2 (at 298 K/1 bar). Furthermore, the isotherms of CO2 gas adsorption and desorption in the porous polymer are reversible. The use of PSB having effective imide, imine, and meta-hydroxyl functional groups in the adsorption and selectivity of CO2 gas produced excellent results, which make it a suitable candidate for CO2 storage and separation applications.
