Enhancement of the gas separation properties of polyurethane membranes by alumina nanoparticles

In this work, polyurethane (PU) nanocomposite membranes were prepared using different concentrations of alumina (Al2O3) nanoparticles (0, 2.5, 5, 10, 20, and 30 wt%). The main objective of this work is to evaluate the permeability of CO2. CH4, O-2, and N-2 gases in the polyurethane hybrid membranes at various Al2O3 contents and with two different chain extenders. Polyurethane was synthesized by bulk two-step polymerization based on polytetramethylene glycol (PTMG) and hexamethylene diisocyanate (HMDI). 1,4-butanediol (BDO) and 2-methyl-1,3-propanediol (MPD) were used as chain extenders to complete the conversion of the prepolymers to the final polyurethanes. The prepared polyurethane-Al2O3 membranes were characterized using Fourier Attenuated Total Reflection-Fourier transform infrared (ATR-FTIR) spectroscopy, scanning electron microscope (SEM), wide angle X-ray diffraction (WAXD), and differential scanning calorimetry (DSC) analyses. The results show a reduction in the gas permeability, but a significant enhancement in the CO2/N-2. CO2/CH4, and O-2/N-2 selectivities with alumina content. The separation performances of the membranes were compared with Robeson's upper bound limit. The new modified Higuchi model was applied to predict the permeability of polyurethane-alumina hybrid membranes. (C) 2015 Elsevier B.V. All rights reserved.