Imine-linked polymer/silica composites for CO₂ sequestration

The silica supported imine polymers are synthesized using a facile single step Schiff-base condensation. The formation of imine linkage on silica support is confirmed using FT-IR and solid state ¹³C NMR. The crystallinity and surface morphology of the materials are examined by PXRD and SEM analyses. The thermal stability of the materials is confirmed from TGA analysis. N₂ sorption isotherms for Si-TPA-1 and Si-TPA-2 exhibit surface area of 105.8 m²/g and 404.5 m²/g respectively. The adsorption isotherms exhibit meso- and microporous environments of Si-TPAs. The CO₂ uptake capacity of Si-TPAs are around 38.86 mg/g - 121. 85 mg/g. The experimental adsorption data is fitted with Langmuir and Freundlich adsorption isotherm models. The thermodynamic parameters emphasis that the adsorption process is spontaneous and exothermic physisorption. Isosteric heats of adsorption for Si-TPAs are around 38.5–32.5 kJ/mol. The high selectivity of CO₂ over N₂ is obtained for both Si-TPAs at 273 K and also high selectivity of CO₂ over CH₄ is achieved at 298 K.