• The driving force of the membrane gas separation process is the difference in pressure of the feed side and the permeate side of the membrane.
• Regardless of the material of the membrane, the feed-to-permeate pressure ratio determines the relative amounts of a component present in the resulting permeate.
• Membrane gas separation tends to be a more efficient method compared to the amine absorption, the method most widely installed currently

      - The absorption is expensive to maintain and operate the systems  

        because it utilizes the corrosive absorbent and require the high​

        energy consumption during the regeneration step of the ​

        absorbent.

     - Polymer membranes are more accessible because the membranes ​

        are relatively less expensive and easy to manipulate for a large ​

        scale setting.

​

• RUBBERY POLYMER MEMBRANES :

      - PRO : relatively high CO2 permeability and CO2/N2 selectivity

      - CON : the tendency of crystallization. (lowers gas permeability)

​​​

• FACILITATED TRANSPORT MEMBRANES :

      - Fixed site carrier facilitated transport membranes are more

        favorable than those of mobile carriers.

       - Facilitated transport membranes (PVAm/PVA) contain amine groups.

       - Compared to the dry state, the PVAm/PVA membranes display better

        CO2 permeance and very high CO2/N2 selectivity in the presence of

        H2O



            2CO2 + 2RNH2 + H2O <---> RHNCOOH + RNH3+ + HCO3-