Silver inclusion polybenzoxazine xerogel membrane for CO₂/CH₄ separation

The effect of silver ion incorporated with a novel organic polybenzoxazine xerogel (PBZ) was investigated as a membrane for flue gas separation. The fully cured interconnected polybenzoxazine xerogel was impregnated with silver nitrate solution. The exothermic peak of polybenzoxazine disappeared after being fully polymerized as observed by DSC. FT-IR results indicated the chemical reaction between the N-Ag. The char yield of Ag+-included in the polybenzoxazine membrane increased rapidly with the increasing of the metal salt concentrations which might be due to the complex formation between metal ions and polybenzoxazine, resulting in more stable cyclic compounds that could form char during the heat treatment. However, the BET results and SEM micrographs showed no change in physical properties of PBZ after Ag+ inclusion. (The ideal separation of flue gas (CO2, N2 and CH4) has been investigated). Interestingly, the CO2 /CH4 selectivity was also increased with the incorporation of Ag+ ion since CO2 molecules containing double bonds could react reversibly with these noble metal ions to form the π -bonded complex, thus obtaining good separation performance.