DEA-Impregnated Cross-Linked Polyvinyl Alcohol/Glutaraldehyde Polymeric Systems as CO2/CH4 Gas Separation Membranes

Developing new methods and technologies for CO2 removal with a variety of applications, such as purification of synthesis gas, natural gas sweetening, and greenhouse gas sequestration are nowadays carried out in research works involving polymeric membranes. By employing suitable reactive carriers into the membrane matrix, the solubility and absorption rate of the reactive gas (i.e., CO2) are enhanced. In facilitated transport membrane, the selective transport through the membrane occurs owing to a reversible reaction between the reactive carriers and the target gas, while in contrast the solution-diffusion is the dominant mechanism for permeation of inert gases such as CH4, N2 and H2. In this work, the cross-linking of diethanolamine (DEA)-impregnated polyvinyl alcohol (PVA) by glutaraldehyde (GA) with different blend compositions (GA/PVA: 0.5, 1, 3, 5, 7 ratio%) were performed in the absence of an acid catalyst and organic solvents in order to avoid any interference in CO2 facilitation reaction with DEA. The fabricated membranes were characterized by differential scanning calorimetry, Fourier transform infrared (FTIR) and scanning electron microscopy. Furthermore, the effects of cross-linking agent content and feed pressure on CO2/CH4 transport properties were investigated in pure gas experiments. Finally, the cross-linked membranes showed reasonable CO2/CH4 permselectivity indexes in comparison to uncross-linked membranes. The best-yield in CO2-selective membranes (DEA-PVA/GA (1 wt%)/PTFE) represented the best CO2/CH4 selectivity of 91.13 for pure gas experiments.