| Silicone rubber (PDMS) is used as a membrane material for gas separation. PDMS has high permeability for oxygen, but low selectivity for oxygen and nitrogen, which has constrained its application. Crosslinking is one of the ways to improve selectivity because the method can reduce the size of spaces between molecular, but permeability may be reduced. To add cobalt(II) complex into PDMS membrane can improve the permeability and selectivity simultaneously, because cobalt(II) ion has facilitated the transportation of oxygen.By the polyetherimide porous membrane used as a supporting layer, the silicone rubber containing vinyl groups of 5 mol% is crosslinked to form a crosslinked membrane. The cyclomolecular crosslinking agent can prevent permeability from being too low.Electropolar solvent such as THF may destroy the polyetherimide layer,while non-electropolar solvent such as petroleum ether cannot solve vinyl acetic acid cobalt.The problem is resolved by the way of solvent replacing.Supporting layer improves the mechanical properties in industrial application. The results show that the membrane has better permeability and selectivity. For example, the permeability velocity (Ro2) for oxygen is 2.181 ×10-5 cm3/cm2·s·cmHg, while the selectivity factor (αo2/N2) is 3.41 under pressure difference of 0.05 MPa and 20℃.The trimethylsilyl methylcellulose(TMS-MC) is added into the membrane material to form a TMS-MC/PDMS/PEI crosslinked membrane. The results show that the selectivity for oxygen and nitrogen has been improved obviously due to the addition of TMS-MC, while the permeability velocity for oxygen is decreased.
|
PDF Full Text Request