Mixed Matrix Membranes Comprising Of Matrimid and –SO3 Funtionalized Mesoporous MCM-41 For Gas Separation

The upper bound curve reported by Robeson suggests that the current polymeric based materials have reached a permeability-selectivity tradeoff. This demands the discovery of new materials and procedures for the synthesis of novel membranes with improved performance. One of the emerging strategy to enhance the performance of membrane materials involves the fabrication of mixed matrix membranes (MMMs) by dispersing inorganic filler particles in polymers matrices. These membranes combine the processability and low cost of polymers with superior permselective properties of fillers. Depending on the type and loading of the fillers, MMMs could result in significantly lowering the cost of membranes in comparison to their expensive inorganic counterparts. However, the synthesis of MMMs is accompanied with several challenges. One of the important criterion is to achieve good contact between the filler and polymer matrix.

In this work, MMMs composed of Matrimid and -SO₃ functionalized mesoporous silica spheres were prepared by the solution casting method. CO₂ permeation data and SEM images of the synthesized MMMs suggest that the fillers adhered well to the polymer matrix. Gas permeation tests indicated that the addition of functionalized MCM-41 to polymer matrix increases both the gas permeability and selectivity. Pure and mixed-gas permeation data showed a substantial increase in CO₂ permeability and selectivity with increased loading of –SO₃ functionalized MCM-41. This behavior resulted from the increase in the content of polar –SO₃ sites, the introduction of fixed mesopores by the filler and disruption of the polymer chain packing by the addition of fillers. The highest ideal selectivities obtained here for CO₂/N₂ and CO₂/CH₄ were 46.97 and 52.48, respectively. In order to evaluate the practical commercial viability of these membranes, they were tested under different operating pressures and temperatures and the results were plotted on the Robeson trade-off upper-bound. The observed increase in permeability and selectivity makes –SO₃ based mesoporous MCM-41 promising fillers for gas separation membranes.