Performance Characteristics and Optimization of a Single-Stage Direct Air Capture Membrane System in Terms of Process Energy Intensity

The increase in emissions and concentration of carbon dioxide in the atmosphere necessitates the implementation of direct carbon dioxide capture technologies. The article presents the characteristics of a single-stage membrane unit for the direct capture of carbon dioxide from the air. A membrane with a selectivity of (Formula presented.) and permeability (Formula presented.) is chosen as the reference variant. It is demonstrated that increasing the pressure difference in the system by reducing the pressure of the permeate stream results in an improvement of all analyzed parameters. Manipulating both the membrane surface and its CO₂ permeability yields similar results. With an increase in permeability or membrane surface area, the proportion of CO₂ in the retentate and permeate decreases, while the degree of carbon dioxide recovery increases. However, the energy intensity of the process is a complex issue due to the presence of a local minimum in the obtained characteristics. Therefore, a relationship between the constants of energy intensity values for the separation process on the surface area field and CO₂ membrane permeability is presented. The minimum energy intensity of the process obtained is 22.5 (Formula presented.). The CO₂ content in the retentate for all analyses did not exceed 280 ppm.