Gas Permeation Study Using Porous Ceramic Membranes

A 6000 nm ceramic membrane was repaired with boehmite solution (ALOOH) through the repeat dip-coating technique. The permeance of hydrogen (H2) and carbon dioxide (CO2) were obtained through the membrane in relation to average pressure at room temperature for the support membrane and as cracked membrane. A repair process was carried out on the cracked membrane by same dip coating process and results obtained after first and second dips. The permeance of the support membrane obtained ranged between 1.50 to 3.04 × 10-7 mol m-2 s-1 Pa-1. However, as a result of a crack that occurred during the removal of the membrane from the reactor, the permeance increased from 2.96 to 5.82 10-7 mol m-2 s-1 Pa-1. Further application of boehmite solution on the membrane lead to an improvement on the surface of the membrane with some degree and surface cracks were reduced. This also decreased the permeance to 1.26 – 3.39 × 10-8 mol m-2 s-1 Pa-1 after the second dip. Consequently, another silica based modified membrane was used for carbon dioxide and nitrogen (N2) permeation. The plots show that carbon dioxide permeated faster than the other gases, indicating dominance of a more selective adsorptive transport mechanism. Accordingly, results obtained show an appreciable high carbon dioxide permeance of 3.42 × 10-6 mol m-2 s-1 Pa-1 at a relatively low pressure when compared to nitrogen confirming that the membrane has so far exhibited a high permeability, selectivity and high CO2 gas recovery. The permselectivities of CO2 over H2 at room temperature was also obtained which were higher than the Knudsen selectivity.