Membrane technology for carbon capture sequestration and direct air capture – Current status and Perspective

To limit warming to less than 2 °C by the end of this century, enormous R&D efforts towards carbon capture have been made. Membrane gas separation is a promising technology for carbon capture and sequestration (m-CCS) due to its higher energy efficiency and smaller carbon footprints than the traditional amine scrubbing methodology. However, CCS alone for carbon capture mainly from stationary industry emitters is insufficient to effectively lower the ambient CO₂ concentration. Complementarily, carbon capture directly from ambient air (DAC) is largely required. The current DAC technology mainly focuses on liquid and solid sorbents which is energy-intensive for regeneration. Membrane gas separation for DAC (m-DAC) was rarely discussed due to the extremely diluted CO₂ concentration (0.04 %) relative to flue gas (∼ 10–15 %) until the very recent process simulation revealed the technological possibility. Herein, we will present the current status of membrane technology for both CCS and DAC in terms of their pilot scale application and the potential applicable membrane materials including polymer-based membranes, inorganic membranes, and facilitated transport membranes. Technology possibility and energy consumption compared with bench-mark sorbents were specifically illustrated for m-DAC. Membrane performance with CO₂ of more than 2,500 GPU and CO₂/N₂ selectivity of more than 680 was regarded as a rough goal for promising membrane materials applied to the m-DAC event based on a primitive energy consumption calculation. Challenges, conclusions, and prospects for m-CCS and m-DAC were made at the end of this review.