Gas Permeation Study Using Porous Ceramic Membranes

Abstract

A 6000 nm ceramic membrane was repaired with boehmite solution (ALOOH) through the repeat dip-coating technique. The permeance of hydrogen (H 2 ) and carbon dioxide (CO 2 ) 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 (N 2 ) 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 CO 2 gas recovery. The permselectivities of CO 2 over H 2 at room temperature was also obtained which were higher than the Knudsen selectivity.

Silica Modified Membrane for Carbon Dioxide Separation from Natural Gas

“…8 shows the selectivities of CO 2 over N 2 , H 2 , O 2 , CH 4 and He against feed pressure across silica membrane at room temperature. CO 2 selectivity was obtained using the ratio of permeability of CO 2 to that of each of the other gases (N 2 , H 2 , CH 4 , O 2 and He) at the same pressures and temperatures using equation (5). The ideal Knudsen selectivity value was obtained from the inverse square root of the ratio of the respective gas molecular weight.…”

“…Therefore, it is imperative to build up new effective technologies to mitigate these emissions. Inorganic membranes applications are technically significant in environmental issues like separation, catalytic reactions among others [1,[4][5][6][7]. Inorganic membranes for CO 2 removal can be applied in-situ without any phase change.…”

“…Selectivity is defined as the ratio of the pure component permeabilities (P y and P z ) for single gases. It can be written as; α y,z = P y /P z (5) where P y is the permeability of y component (mol-m/m-2 s-1 Pa-1 ), and P z is the permeability of z component (mol-m/m-2 s-1 Pa-1 ). Surface diffusion has been named as an important mechanism in a number of studies on silica membranes for the selective separation of CO 2 .…”