CO2 adsorption onto 1-butyl-3-vinylimidazolium based poly(ionic liquid)s: experimental and theoretical studies

Poly (ionic liquid)s attracted enormous attention as adsorbents for the CO2 separation from natural gas. Hence, in this work poly (1-butyl-3-vinylimidazolium bromide), P[VBIm][Br], poly (1-butyl-3-vinylimidazolium thiocyanate), P[VBIm][SCN], and poly (1-butyl-3-vinylimidazolium tetrafluoroborate), P[VBIm][BF4] were synthesized and evaluated their CO2 adsorption performance. The synthesized poly(ionic liquid)s were characterized by H-1 NMR, FT-IR spectroscopy, and differential scanning calorimetery (DSC) analysis. The CO2 adsorption was studied at various temperatures and pressures by quartz crystal microbalance (QCM) and experimental data were correlated by a model of dual-mode. The Henry and Langmuir contributions in CO2 adsorption were evaluated. The obtained thermodynamics and kinetics parameters of CO2 adsorption reveal that CO2 adsorption has an exothermic and physisorption nature. Also, density functional theory (DFT) computations were done in order to assess interactions between poly(ionic liquid)s with CO2 gas. DFT computations corroborated that interaction of P[VBIm][SCN] with CO2 is stronger than those of other poly(ionic liquid)s.

Automated summary

This study evaluates the CO2 adsorption performance of several poly(ionic liquid)s and confirms that CO2 adsorption is exothermic and based on physisorption. Experimental and computational analyses show that the interaction between P[VBIm][SCN] and CO2 is stronger compared to other poly(ionic liquid)s.