SYNTHESIS AND CHARACTERIZATION OF SILYLATED MCM-41/POLYSULFONE MIXED MATRIX MEMBRANE FOR CO2/CH4 SEPARATION

Since the polymeric membrane is not able to fulfill the requirements of industrial application, mixed matrix membrane (MMM) has been used for gas separation purposes. However, the incompatibility between polymer matrix and inorganic filler remains as a major concern in MMM development. In this work, polysulfone (Psf) is incorporated with silylated MCM-41 to form MMMs. Mobil Composition of Matter No. 41 (MCM-41) is chosen as the inorganic filler because its mesoporous structure is suitable for gas separation applications. MCM-41 was synthesized via templating method and subsequently modified by surface silylation using trimethylchlorosilane (TMCS) to enhance its hydrophobicity for enhanced dispersion and adhesion in mixed matrix membranes. Structural modifications of MCM-41 after silylation are observed in FT-IR, XRD. SAP analysis indicates that silylated MCM-41 achieves higher surface area (1058.86 m2/g) and reduced pore size (2.05nm). The critical polymer concentration of Psf was studied to suppress the formation of macro-voids in mixed matrix membranes. The critical concentration of Psf in chloroform solvent is 23wt.%. Flat sheet Psf/silylated MCM-41 membranes were then fabricated by dry phase inversion method with different loadings of MCM-41 in Psf matrix. For the cross-sectional morphologies, MMMs with silylated MCM-41 indicates good distribution and dispersion whereas there is appearance of cluster representing particle agglomeration in MMMs with unmodified MCM-41. Differential scanning calorimetry (DSC) was applied to investigate the glass transition temperature of the resultant membranes. The incorporation of silylated MCM-41 into Psf matrix has increased the thermal stability of the membrane. With 5wt.% of silylated MCM-41, CO2 gas permeability of the MMM is shown to increase by 113.6% when compared to the pure Psf membrane. In addition, silylation of MCM-41 enhances the CO2/ CH4 selectivity of resultant MMM from 28.04 to 30.89.