Simultaneously enhanced gas permeability, selectivity and aging stability of carbon molecular sieve membranes by the molecule doping of silicon.

Simultaneously enhancing the gas permeability, selectivity and aging stability of carbon molecular sieve membrane (CMSM) is extremely difficult. Facing such poser, a novel silicon doped CMSM at molecular level was prepared by copolymerizing siloxane with single Si– O –Si unit into the backbone of polyimide (PI). This can effectively avoid prior separated structure or multiple Si– O –Si structures and strongly alter the chains packing and thermostability of PI, finally determine the pore structure and thermodynamic behavior. The simple design adjustment simultaneously exhibits the triple enhanced effects on the gas permeability, selectivity and aging stability. The best molecule doped CMSM exhibits the ultra-high H 2 permeability (12482 Barrer, 87% higher), 26% higher H 2 /CH 4 selectivity, and 32% higher H 2 /N 2 selectivity than pure PI based CMSM. Additionally, such CMSM also has a much better aging stability than pure CMSM and most reported CMSMs. After stabilization, it still maintains a high H 2 permeability (8000 Barrer). And the hyper-aging CMSM also exhibits a good aging resistance showing a H 2 permeability of 5300 Barrer, as well as high selectivity of H 2 /CH 4 (125) and H 2 /N 2 (106) after 35 days. This work opens a new way on designing CMSM with excellent performance through heteroatom doping to need future application. [Display omitted] • A novel molecule doping of silicon in CMSMs was achieved. • The addition of siloxane affects the packing and decomposition of PI chains. • Both gas permeability and selectivity of CMSMs were improved. • The silicon doped CMSM exhibited excellent aging stability. • The aged CMSM maintains a high H 2 permeability of 8000 Barrer. [ABSTRACT FROM AUTHOR]