Polymeric Membrane Models increasing permeability

Reports are also available on CO2 selective membrane reactors for WGS reaction. Zou et al. [40] first time synthesized polymeric C02-selective membrane by incorporating fixed and mobile carriers in cross-linked poly vinyl alcohol. Micro-porous Teflon was used as support. They used Cu0/Zn0/Al203 catalyst for low temperature WGS reaction. They investigated the effect of water content on the CO2 selectivity and CO2/H2 selectivity. As the water concentration in the sweep gas increased, both CO2 permeability and CO2/H2 selectivity increased significantly. Figure 6.18 shows the influence of temperature on CO2 permeability and CO2/H2 selectivity. Both CO2 permeability and CO2/ H2 selectivity decrease with increasing reactimi temperature. After the catalyst activation, the synthesis gas feed containing 1% CO, 17% CO2, 45% H2 and 37% N2 was pumped into the membrane reactor. They are able to achieve almost 100% CO conversion. They also developed a one-dimensional non-isothermal model to simulate the simultaneous reaction and transport process and verified the model experimentally under an isothermal condition. 

As mentioned in the beginning, increased membrane stability is not sufficient to build better biomembrane models. The stabilized systems have also to be able to perform biological membrane properties such as selective permeability. Since the polymerized systems discussed so far combine increased stability with significantly decreased permeability, methods have to be found to selectively open up these stabilized membrane systems, A basis for this could be the incorporation of labile components into the polymerizable system which could be destabilized, for instance, by variation of pH (28), photochemical isomerization (29) or enzymatic hydrolysis. 

---