Facile fabrication of hybrid carbon molecular sieve membranes based on β-cyclodextrin/polyimide for efficient gas separation

Abstract

The development of high-performance carbon molecular sieve (CMS) membrane materials is critical to advancing next-generation gas separation technology. In this work, β-cyclodextrin (β-CD) was incorporated into polyimide (PI) through a straightforward solution-casting process to fabricate hybrid precursor membranes, which were subsequently carbonized into hybrid CMS membranes. By optimizing both β-CD content and carbonization temperature, the resulting hybrid CMS membranes exhibited exceptional gas separation performances. Under optimal conditions, the hybrid membranes with 3% β-CD, carbonized at 550 °C demonstrated extraordinarily enhanced gas permeability (PCO2=6634.4 Barrer, PH2=15535.3 Barrer, and PHe=4282.9 Barrer, together with significantly improved gas selectivties (αCO2/N2=33.1, αCO2/CH4 =40.0, αH2/N2 =66.5, and αH2/CH4 =79.5), which is 159%, 217%, 536% and 736% times of the pure PI precursor, and surpassing the latest Robeson upper bound for H2 and CO2 separation. The high separation performances together with its facile blending preparation method, making it promising for gas separation.