CO₂/N₂ gas separation using Fe(BTC)-based mixed matrix membranes: A view on the adsorptive and filler properties of metal-organic frameworks

The incorporation of a Metal-Organic Framework (MOF), Fe(BTC), into a polymeric membrane was assessed for CO₂/N₂ gas separation. The adsorptive and filler properties of the MOF in the Mixed Matrix Membranes (MMMs) produced were investigated as a strategy to separate CO₂ from N₂ and contribute to reduce CO₂ emissions. Therefore, Fe(BTC) was firstly characterized by single-component adsorption equilibria measurements of CO₂ and N₂, to evaluate the MOF performance as an adsorbent for CO₂/N₂ separation and its adsorption role in the MMMs performance. Fe(BTC) was then incorporated in Matrimid®5218 at different loading percentages, and the MMMs produced were characterized by distinct techniques (SEM, TGA, puncture tests and contact angle essays). Finally, pure gas permeation experiments were carried out for CO₂ and N₂ at 303 K, 323 K and 353 K, to evaluate the temperature impact on both gas permeability and CO₂/N₂ ideal selectivity. The results show that an increase in CO₂ permeability and CO₂/N₂ ideal selectivity can be advantageously achieved, especially at the higher operating temperature of 353 K. At these conditions, the Robeson upper-bound is surpassed, which is a clear indication of the high potential of using Matrimid®5218/Fe(BTC) MMMs in post-combustion streams at high-temperatures.