Mesoporous silica based composite membrane formation by in-situ cross-linking of phenol and formaldehyde at room temperature for enhanced CO2 separation

Abstract

In the present report, composite membranes (CM) were prepared from a resin, derived from phenol and formaldehyde as matrix and mesoporous silica SBA-15 as filler on the clay-alumina tubular support. Membrane matrix was formed by in-situ cross-linking of phenol (P) and formaldehyde (F) at room temperature. The structural changes of membrane matrix with curing time influence the final properties of the membranes. The surface morphology and the filler-polymer interaction i.e. surface silanol group of SBA-15 and –CH2OH/–OH group of P–F resin of composite membrane were established by FESEM and Fourier transformation of infrared spectroscopy (FT-IR) and X-ray Photoelectron Spectroscopy (XPS) respectively. Thermal stability of the membranes was characterized by Thermogravimetric analysis (TGA) and Differential Thermal Analysis (DTA). Finally, the permeability and the separation efficiencies of the developed composite membranes were studied in details with varying curing time of resin at room temperature, feed pressure and different gas compositions for CO2/H2 and CO2/CH4 mixture gases. For CO2/H2 ‘reverse selectivity’ was observed with the membrane. The highest separation factor of CO2/H2 and CO2/CH4 were achieved upto 16.6 and 62.4 for 67:33 (CO2/H2) and 45:55 (CO2/CH4) feed composition respectively. The room temperature cross-linking of P–F resin modified the interfacial defect of membrane and its effect on the CO2 separation efficiencies is the unique observation of the present work. The obtained permeability and selectivity values of different gases were surpassing the 2008 Robeson upper bound line.