Cellulose acetate/nano-porous zeolite mixed matrix membrane for CO2 separation

The aim of this research is to investigate the fabrication and evaluation of a new mixed matrix membrane for CO2/N-2 separation. Micro-sized nano-porous sodium zeolite-Y (NaY zeolite) particles (0-25 wt.%) were incorporated into the dense (homogeneous) cellulose acetate (CA) membrane to prepare the CA/NaY mixed matrix membranes. One of the most important features of this study is to explore the simultaneous effect of annealing and particle loadings on the morphology and gas permeation properties of the prepared membranes. The membranes were characterized by Fourier transform infrared spectroscopy - attenuated total reflectance (FTIR-ATR) and scanning electron microscopy (SEM) analyses. Also, the CO2/N-2 separation performance of the membranes was evaluated by single gas permeation measurements. The results showed that annealing causes a considerable improvement in the morphology of the CA and the related mixed matrix membranes. Additionally, more than a two-fold increase in CO2 permeability with no considerable decrease in CO2/N-2 selectivity was achieved by a 20 wt.% NaY loading into the CA membrane. The results of investigating the effect of pressure (4-22 bars) on CO2 permeability showed a reduction in the CO2-induced plasticization of glassy CA with a significant shift in the plasticization pressure toward higher values. The introduction of NaY zeolite in the annealed CA membranes, shifted the plasticization pressure from 12.76 to 16.86 bars when the zeolite loading was changed from 0 to 25 wt.%.