Preparation Of Poly ?Ionic Liquid?s And Application In CO₂ Adsorption

In recent years, excessive consumption of fossil fuels caused higher CO2 concentration in atmosphere and arose the greenhouse effect, which resulted in a series of serious environmental problems, such as glaciers melting and sea levels rising, etc. The CO2 emission reduction is very urgent in the global. Carbon Capture and Storage (CCS) is a kind of effective technology. Ionic liquids (ILs) can be used for CO2 capture and separation because of high solubility and selectivity with CO2. But high viscosity limits its application in the industry. Poly (ionic liquid)s (PILs) have many advantages which combine ionic liquids and polymers. PILs have good CO2 adsorption capacity as ILs, meanwhile PILs are designable and have stable structure. In this paper, five types of PILs were synthesized and the CO2 adsorption capacity was investigated.Firstly, we synthesized two kinds of quaternary ammonium PILs: P[VBTEA]C1, P[VBTHEA]C1 and three kinds of imidazole PILs:P[VEIm]Br, P[VEIm]BF4, P[VEIm]PF6. All of the PILs were polymerized by free-radical polymerization in solution and characterized by FT-IR,'H-NMR,13C-NMR, TGA, DSC, XRD, SEM. The structures and properties of PILs were analyzed. FT-IR,1H-NMR and 13C-NMR indicated that PILs were synthesized successfully. TGA indicated polymers had good thermal stability. DSC, XRD and SEM indicated polymers were amorphous.Then we tested CO2 adsorption capacity of quaternary ammonium and imidazole PILs under different pressure and temperature by constant-volume technique. The experimental results showed that cations and anions had an effect on the CO2 adsorption capacity. The CO2 adsorption capacity of quaternary ammonium PILs with same anions (Cl-) and skeleton followed the order:P[VBTHEA]C1> P[VBTEA]C1; the CO2 adsorption capacity of imidazole PILs with same cations ([VEIm]+) and skeleton followed the order: P[VEIm]PF6> P[VEIm]BF4> P[VEIm]Br. In the five types of PILs, P[VBTHEA]C1 had the highest CO2 adsorption capacity of 9.02 mg/g under 295K, 1bar. The CO2 adsorption capacity of PILs was much higher than the corresponding monomer ILs. PILs had good adsorption selectivity, which adsorbed CO2 rather than other gas. After four adsorption cycles, the regeneration efficiency of PILs was up to 96.1%. In conclusion, PILs are a kind of promising CO2 adsorbent.