Abstract
We synthesized one quaternary ammonium polymeric ionic liquids (PILs)P[VBTHEA]Cl and three imidazolium PILs of P[VEIm]Br, P[VEIm]BF4, P[VEIm]PF6 by free-radical polymerization in solution. These PILs were characterized by FT-IR, 1H-NMR, 13C-NMR, TGA, XRD and SEM. Their CO2 adsorption capacities were measured under different pressures and temperatures by constant-volume technique. It was observed that quaternary ammonium PILs of P[VBTHEA]Cl have higher adsorption capacity for CO2 than those imidazolium PILs, following P[VBTHEA]Cl>P[VEIm]PF6>P[VEIm]BF4>P[VEIm]Br, which may be ascribed to higher positive charge density on ammonium cation than that on imidazolium cation and thus stronger interaction with CO2, consistent with the results from dual-mode adsorption model that ammonium PILs have much higher CO2 bulk absorption than imidazolium PILs. CO2 adsorption capacity of P[VBTHEA]Cl is 9.02mg/g under 295K and 1bar, which is comparable to that of some other PILs, and is much higher than that of the corresponding ILs monomer. These PILs have good adsorption selectivity for CO2 over N2 and regeneration efficiency.
A new class of CO2 adsorbents: polymeric ionic liquids material with high CO2 adsorption capacity & selectivity and good cycling. [Display omitted]