Homogenization of the Dense Composite Membranes …
53
the good selectivity of the carbon dioxide versus hydrogen may be obtained only if
the solubility of the carbon dioxide is increased as much as possible. Although the
masses and dimensions of the molecules of both oxygen and nitrogen are smaller in
comparison with carbon dioxide, the difference is not so high as in the case of the
hydrogen, so the difference in diffusion coefficients will also be smaller. Anyway, in
order to provide good separation, the solubility of both oxygen and nitrogen should
remain at the lowest possible level [21–25].
As an additive for better solubility of the carbon dioxide, various zeolite powders
may be added. Zeolites are various minerals based on the aluminosilicates with a
framework that can accommodate dissolved molecules of the carbon dioxide. If the
powders are applied as additives to the polymers for the carbon dioxide separation,
zeolite powders should be dispersed in the same solvent as polymer. This step is
important in order to obtain thin membrane with a smooth surface. The main challenge in this process is to provide good contact between highly polar, hydrophilic inorganic zeolite particles and hydrophobic, hydrocarbon chains of the polymer. Possible
approach is to add different additives whose task would be to provide good contact
between polymer chains and zeolite particles, resulting in homogenous, smooth,
pinholes’ free membranes.
Materials and Methods
In this study, mixing properties and possibility of application of two different polymers were tested. The structures of the polymers used in this work are presented in
Fig. 1 (PEBAX) and Fig. 2 (Polyactive).
Fig. 1 Structure of the PEBAX 1657 used as a matrix for group of the membranes
Fig. 2 Structure of the polyactive used as a matrix for group of the membranes
53
the good selectivity of the carbon dioxide versus hydrogen may be obtained only if
the solubility of the carbon dioxide is increased as much as possible. Although the
masses and dimensions of the molecules of both oxygen and nitrogen are smaller in
comparison with carbon dioxide, the difference is not so high as in the case of the
hydrogen, so the difference in diffusion coefficients will also be smaller. Anyway, in
order to provide good separation, the solubility of both oxygen and nitrogen should
remain at the lowest possible level [21–25].
As an additive for better solubility of the carbon dioxide, various zeolite powders
may be added. Zeolites are various minerals based on the aluminosilicates with a
framework that can accommodate dissolved molecules of the carbon dioxide. If the
powders are applied as additives to the polymers for the carbon dioxide separation,
zeolite powders should be dispersed in the same solvent as polymer. This step is
important in order to obtain thin membrane with a smooth surface. The main challenge in this process is to provide good contact between highly polar, hydrophilic inorganic zeolite particles and hydrophobic, hydrocarbon chains of the polymer. Possible
approach is to add different additives whose task would be to provide good contact
between polymer chains and zeolite particles, resulting in homogenous, smooth,
pinholes’ free membranes.
Materials and Methods
In this study, mixing properties and possibility of application of two different polymers were tested. The structures of the polymers used in this work are presented in
Fig. 1 (PEBAX) and Fig. 2 (Polyactive).
Fig. 1 Structure of the PEBAX 1657 used as a matrix for group of the membranes
Fig. 2 Structure of the polyactive used as a matrix for group of the membranes