A new relevant membrane application: CO₂ direct air capture (DAC)

Highlights

• Membranes as a promising tool for CO₂ capture.

• A perspective on direct air capture (DAC) from atmosphere is given.

• Process considerations to make DAC feasible are addressed.

• Advantages and drawbacks of membranes over other DAC technologies are provided.

• An outlook of DAC using membranes is elucidated.

Abstract

Since carbon dioxide (CO₂) is the primary greenhouse gas emitted into the atmosphere due to human activities, strong research efforts have been developed towards capturing and decreasing its production. Unfortunately, specific processes and activities make it impossible to avoid CO₂ emissions. Among the different strategies scientists propose for CO₂ reduction, direct CO₂ capture from the atmosphere, also known as direct air capture (DAC), represents a promising alternative in which sorbents have been mainly used. Recently, gas separation membranes have also been speculated to carry out such a separation, thanks to their smaller footprint and simpler setup and operation; however, their application remains a proposition in the field. This paper gives a perspective of the ongoing research and attempts of DAC applications via membrane separation and introduces the main membrane materials and types used for CO₂ separation. Finally, the process considerations for DAC using membranes are stated to guide the new researchers in the field.