Preparation and gas permeation of nano-sized zeolite NaA-filled carbon membranes

Nano-sized zeolite NaA crystal-filled carbon membranes were prepared on the inner surface of porous tubular alumina supports by dip-coating method, using the precursor solutions prepared by dispersing different amounts of nano-sized zeolite NaA particles in the alcohol solutions of phenolic resin. Single gas permeation measurements were carried out to examine the gas separation properties of the membranes. It was found that the zeolite NaA-filled carbon membranes showed higher ideal selectivities but lower single gas permeances than the pure carbon membranes when all the membranes were prepared with two cycles of preparation processes. When the nano-sized zeolite NaA content was 2 wt.% in the precursor solution, the resulting carbon membrane exhibited highest O₂/N₂ permselectivity of 14.6 and CO₂/N₂ permselectivity of 159. Higher or lower zeolite NaA content than 2 wt.% in the precursor solutions resulted in lower ideal selectivities of the gas pairs of the corresponding membranes. The change of the gas permeance with temperature of the zeolite NaA-filled carbon membrane was similar to that of the pure carbon membranes, indicating the similar gas permeation mechanism through the two kinds of membranes.