Polysulfone Hollow-Fiber Membranes for Post-Combustion CO₂ Capture: Fabrication, Process Modeling, and Experimental Validation of a Continuous Membrane Column

This work presents an integrated experimental and modeling study of post-combustion CO₂ capture using polysulfone hollow-fiber membranes in a three-module «Continuous Membrane Column» cascade. Polysulfone hollow fibers were fabricated by dry–wet spinning, defect-healed with silicone, and characterized using both single gases and a humid four-component flue-gas mixture containing N₂/O₂/H₂O/CO₂ = 73.0/4.4/11.0/11.6 mol.%. The selected membrane exhibited a mixed-gas CO₂ permeance of 117 GPU with CO₂/N₂ and O₂/N₂ selectivities of 21.3 and 4.1, respectively. These experimentally determined transport parameters were implemented directly in an Aspen Plus model of the cascade. Two complementary simulation cases were considered: a process-scale calculation used for membrane-area sensitivity analysis and a laboratory-scale calculation using the actual membrane areas and feed-flow range employed in the experiments. In contrast to our previous studies, which were limited to process simulation, the present work extends the «Continuous Membrane Column» concept to full experimental validation using independently fabricated hollow-fiber membranes and a humid multicomponent feed. Both simulation scales predicted essentially the same characteristic behavior, with increasing overall stage cut leading to higher CO₂ recovery, lower residual CO₂ concentration, and reduced product purity. At the upper part of the investigated stage-cut range, the experimental CO₂ recovery reached approximately 80–81%, compared with approximately 82–83% predicted by the laboratory-scale model; the residual CO₂ concentration decreased below 1 mol.% experimentally, compared with approximately 1.8–1.9 mol.% predicted, while the product CO₂ concentration was approximately 67–70 mol.% experimentally and approximately 68–70 mol.% in the simulation. The results demonstrate that the model correctly reproduces the principal purity–recovery trade-off and the relevant operating window, while the remaining quantitative deviations indicate the influence of non-ideal hydrodynamic and engineering effects not captured by the idealized membrane-module description.