Preparation and characterization of polyvinyl acetate/zeolite 4A mixed matrix membrane for gas separation

Abstract

The demand and consumption of fossil fuels have increased in the past and continue to increase in future. The combustion of these fossil fuels produce various harmful gases i.e CO2, SO2, H2S etc. that pose potential threat to the environment. Currently the development of new membrane materials is the focus of research in membrane based gas separation. Pure PVAc and PVAc/4A mixed matrix membranes were prepared using dichloromethane as a solvent and the solution casing method. The resulting membranes were characterized by optical microscope, FESEM, DSC, TGA, XRD and single gas permeation. Optical microscope was used to find out the initial thickness of membranes that ranges from 70μm to 90μm. Zeolite 4A particles upto 35wt% were homogenously dispersed within the polymer without aggregation as shown by the FESEM results. The addition of 4A particles have improved the thermal stability of PVAc in the resulting MMMs as depicted by an increase in the glass transition temperature (Tg) and TGA results. In single gas permeation, the effects of zeolite 4A loading, operating temperature and pressure on the separation properties were investigated. The obtained results show that the addition of zeolite 4A up to 25wt% has increased the selectivity of gas pairs O2/N2, H2/N2 and CO2/N2 by 25%, 37% and 70% respectively with a corresponding decrease in their permeability. Temperature increase from 30°C to 50°C has a positive effect on permeabilities with a maximum of (1.19)×3.348×10−19kmolm/(m2sPa) (barrer) for O2, (17.55)×3.348×10−19kmolm/(m2sPa) (barrer) for H2 and (9.35)×3.348×10−19kmolm/(m2sPa) (barrer) for CO2 and a negative effect on their selectivity over N2. As the pressure is increased from (2)×100,000Pa (bars) to 8×100,000Pa (bars), permeability of H2 almost remains constant and slightly increases for O2. Permeability of N2 and CO2 is decreased and increased respectively leading to increased selectivity of CO2/N2 as well as H2/N2 and O2/N2. The obtained results are consistent with the reported literature data.