Research Progress of CO2 Capture and Membrane Separation by Pebax Based Materials

Membrane separation technology for CO2 is a critical means of achieving the carbon peaking and carbon neutrality goals, and the performance of membrane materials significantly impacts the effectiveness of membrane separation. Polyether block amide (Pebax), known for its high permeability and selectivity towards (CO2), along with high mechanical strength and excellent chemical stability, is a highly promising polymer for gas separation membrane materials due to its cost-effectiveness. However, the permeability and selectivity of pure Pebax membranes for CO2 are still constrained by the "trade-off " effect. Therefore, the future development direction involves the physical or chemical optimization of Pebax to enhance its gas separation performance. This review introduces the characteristics of Pebax-based membrane materials for CO2 capture and explores the factors influencing their gas separation performance. The emphasis is on optimizing Pebax preparation processes, promoting transfer membranes, crosslinking, and blending four types of ultra-thin Pebax composite membranes. Additionally, the paper reviews the research progress on Pebax-based mixed matrix membranes and filler functionalization. From the perspective of process improvement, methods such as choosing a shorter chain length of polyamide (PA), increasing casting solution concentration, using solvents with dissolution parameters closer to Pebax, and employing lower drying temperatures contribute to the formation of more regular and higher crystallinity membranes, enhancing gas membrane separation selectivity. Combining grafting, plasma treatment, and other techniques in the preparation of composite membrane materials allows for minimizing the thickness of the Pebax layer to maximize permeability. In facilitated transport membranes, further research is required to explore the "competition-promotion" relationship between water and CO2 transport for different CO2 carriers. Reducing the free water content in the membrane will directly limit the generation of (CO2) carriers like bicarbonate, potentially hindering CO2 dissolution in coordination with functional groups such as carboxylic acids. To overcome the limitations of a single material and achieve new properties that a single component cannot attain, the review suggests selecting multiple polymers or fillers with favorable physical and chemical properties and compatibility at the polymer-filler interface to prepare mixed matrix membranes (MMMs). Choosing porous fillers or polymer materials with good synergistic effects, constructing ternary or even quaternary systems, and directionally controlling the membrane's pore structure and hydrophilic-hydrophobic characteristics hold the potential to break through the trade-off relationship while obtaining superior mechanical strength, durability, and tolerance to harsh operating environments. In conclusion, based on the above findings, this review provides a perspective on the future optimization directions for Pebax-based membrane materials, addressing the current trade-off between permeability and selectivity.