Permeation Behavior of single and Mixed Gases through Mixed Matrix Membranes

Abstract

CO2 presence in natural gas decreases the calorific value which makes its separation indispensable. Most of the polymers or their blends used for CO2 separation are very expensive but cellulose acetate (CA) being cheap is a lucrative choice. Polyethylene glycol (PEG) has been utilized to enhance the chain flexibility of polymers which in turn modifies the permeability of different gases through these polymers while CNTs provides an extra free path for CO2 molecules and augment its permeability. In this research, PEG and multi-wall carbon nanotubes (MWCNTs) were incorporated in CA using acetone as solvent via solution casting technique to study the permeation behavior of pure and mixed gases (CO2 and CH4) through fabricated membranes. Membranes of pure CA, CA/PEG blend of different PEG concentrations (5%, 10%, 15%) and CA/PEG/MWCNTs blend of 10% PEG with different MWCNTs concentrations (5%, 10%, 15%) were prepared. Fabricated membranes were characterized using scanning electron microscopy (SEM), X-ray Diffraction (XRD), Thermo gravimetric analysis (TGA) and Tensile Testing. Permeation results demonstrate remarkable improvement in CO2/CH4 selectivity. For pure gases CO2/CH4 selectivity is enhanced from 5.74 to 39.47 in the case of 10%PEG/CA however maximum CO2/CH4 selectivity of 48.92 is obtained for 10%MWCNTs/10%PEG/CA. In the case of mixed gas CO2/CH4 selectivity augmented from 2.16 to 28.67 for 10%PEG/CA whereas maximum CO2/CH4 selectivity of 38.5 is documented for 10%MWCNTs/10%PEG/CA.