The 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 for 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 the β-CD content and carbonization temperature, the resulting hybrid CMS membranes exhibited exceptional gas separation performance. Under optimal conditions, the hybrid membranes with 3% β-CD carbonized at 550 °C demonstrated extraordinarily enhanced gas permeability (P_CO2 = 6634.4 Barrer, P_H2 = 15 535.3 Barrer, and P_He = 4282.9 Barrer), together with significantly improved gas selectivities (α_CO2/N2 = 33.1, α_CO2/CH4 = 40.0, α_H2/N2 = 66.5, and α_H2/CH4 = 79.5) which are 159%, 217%, 536% and 736% higher than those of the pure PI precursor and surpass the latest Robeson upper bound for H₂ and CO₂ separation. The high separation performance together with the facile blending preparation method, make them promising for gas separation.