Anion Exchange Membranes Based on Imidazoline Quaternized Polystyrene Copolymers for Fuel Cell Applications

Imidazoline is a five-membered heterocycle derived by the partial reduction of one double bond of the imidazole ring. This work prepared new anion exchange membranes (AEMs) based on imidazoline quaternized polystyrene copolymers bearing N-b-hydroxyethyl oleyl imidazolinium pendent groups to evaluate the application potential for anion exchange membrane fuel cells (AEMFCs). For comparison, an imidazole quaternized polystyrene copolymer was also synthesized. The polymer chemical structure was confirmed by FTIR, NMR, and TGA. In addition, the essential properties of membranes, including ion exchange capacity (IEC), water uptake, and hydroxide conductivity, were measured. The alkaline stabilities of imidazolium-based and imidazolinium-based AEMs were compared by means of the changes in the TGA thermograms, FTIR spectra, and hydroxide conductivity during the alkaline treatment in 1 M KOH at 60 °C for 144 h. The results showed that the imidazolinium-based AEMs exhibited relatively lower hydroxide conductivity (5.77 mS/cm at 70 °C) but much better alkaline stability compared with the imidazolium-based AEM. The imidazolinium-based AEM (PSVBImn-50) retained 92% of its hydroxide conductivity after the alkaline treatment. Besides, the fuel cell performance of the imidazolium-based and imidazolinium-based AEMs was examined by single-cell tests.

CO2 capture by a novel CaO/MgO sorbent fabricated from industrial waste and dolomite under calcium looping conditions

A synthetic sorbent prepared from carbide slag and dolomite by combustion exhibits high CO₂ capture capacity, good cyclic stability and a porous microstructure.

Selective formation of a zwitterion adduct and bicarbonate salt in the efficient CO2 fixation by N-benzyl cyclic guanidine under dry and wet conditions

The efficient CO₂ fixation by N-benzyl cyclic guanidine 1 was achieved by bubbling dry CO₂ through CH₃CN at 25 °C for 2 h. In addition, the zwitterion adduct 2 and bicarbonate salt 3 were selectively prepared from 1 under dry (in anhydrous CH₃CN) and wet (in CH₃CN containing an equimolar amount of water for 1) conditions, respectively. Both compounds 2 and 3 were isolated as white solids and their structures were characterized in detail by elemental analysis, FTIR-ATR, solid-state NMR, TGA, and DFT calculation. These analytical results obviously revealed the formation of a zwitterion adduct and bicarbonate salt from N-benzyl cyclic guanidine and CO₂. Especially, the zwitterion adduct of the monocyclic guanidine derivative and CO₂ was isolated and characterized for the first time.