(646a) Mixed Matrix Membranes for H2/CO2 Separation

We verified the feasibility of mixed matrix membranes based on poly-2-6-dimethylpoly(phenylene oxide) (PPO) for H₂/CO₂ separation in the purification of syngas obtained from coal gasification process. PPO shows a very high permeability but a moderate selectivity for the H₂/CO₂ couple at room temperature. We tried to improve the H₂-selective behavior by incorporating different types of fillers. The preparation protocol was optimized to allow the formation of stable, compact and mechanically robust films up to 50% in weight of filler, with a thickness of around 50 micrometers. It is shown that the evaporation rate is crucial to obtain good films. Pure and mixed matrix membranes were tested via DSC and SEM to verify the thermal behavior and morphology; fillers were analyzed to detect the particle size distribution. The gas transport behavior of the mixed matrix membranes with different filler loadings was tested with Helium, CO₂, N₂ and CH₄ at different temperatures and correlated to the membrane structure and preparation protocol. The effect of membrane annealing on the membrane structure and gas transport was studied, indicating a strong effect of membrane history, especially in the case of hydrophilic fillers.