Thermodynamic efficiency of membrane separation of dilute gas: Estimation for CO2 direct air capture application

Abstract

Gas separation technology is crucial for addressing environmental issues like CO₂ capture to mitigate climate change. While membrane separation is often cited for its efficiency, accurate estimations are scarce. We present estimations based on classical thermodynamics for very lean CO₂ composition (400 ppm), revealing rich details in simple systems and deriving guiding principles. Our main conclusion emphasizes the critical necessity of a high membrane separation ratio, and we discuss candidates for achieving this goal.