Mixed Matrix Membranes for O₂/N₂ Separation: The Influence of Temperature

In this work, mixed matrix membranes (MMMs) composed of small-pore zeolites with various topologies (CHA (Si/Al = 5), LTA (Si/Al = 1 and 5), and Rho (Si/Al = 5)) as dispersed phase, and the hugely permeable poly(1-trimethylsilyl-1-propyne) (PTMSP) as continuous phase, have been synthesized via solution casting, in order to obtain membranes that could be attractive for oxygen-enriched air production. The O₂/N₂ gas separation performance of the MMMs has been analyzed in terms of permeability, diffusivity, and solubility in the temperature range of 298-333 K. The higher the temperature of the oxygen-enriched stream, the lower the energy required for the combustion process. The effect of temperature on the gas permeability, diffusivity, and solubility of these MMMs is described in terms of the Arrhenius and Van't Hoff relationships with acceptable accuracy. Moreover, the O₂/N₂ permselectivity of the MMMs increases with temperature, the O₂/N₂ selectivities being considerably higher than those of the pure PTMSP. In consequence, most of the MMMs prepared in this work exceeded the Robeson's upper bound for the O₂/N₂ gas pair in the temperature range under study, with not much decrease in the O₂ permeabilities, reaching O₂/N₂ selectivities of up to 8.43 and O₂ permeabilities up to 4,800 Barrer at 333 K.