Spirocyclic poly(vinylene ether ketone) membranes with enhanced microporosity for energy-efficient alcohol-hydrocarbon azeotrope separation.

The energy-efficient separation of azeotropic organic mixtures remains a critical challenge in chemical manufacturing. Conventional thermal-driven processes like distillation and pervaporation face fundamental thermodynamic constraints, requiring energy-intensive phase transitions. We present a pressure-driven membrane solution using a spirocyclic poly(vinylene ether ketone) membrane with enhanced microporosity that achieves alcohol-selective permeation from alcohol-hydrocarbon azeotropes. The membrane demonstrates separation factors of 330 for ethanol/cyclohexane and 74 for ethanol/heptane systems, while reducing energy consumption by 2-3 orders of magnitude compared to conventional methods. Through multiscale characterization and molecular dynamics simulations, we elucidate the dual mechanism governing separation performance: differential surface adsorption affinity and restricted hydrocarbon diffusion within micropores of membrane. Here, we show a molecular sieving strategy bypasses traditional volatility-based separation paradigms, offering an approach for azeotrope fractionation with transformative potential for sustainable chemical processing.