Separating carbon dioxide from natural gas by a hollow fiber membrane contactor with various absorbents: Numerical investigation of membrane wettability

This study investigated CO 2 separation from natural gas using hollow fiber membrane contactors, focusing on the combined effects of membrane wettability and absorbent type on separation efficiency. Unlike prior studies that primarily examined dry or fully wetted membranes, we explored intermediate wetting conditions (20 %–60%) to simulate realistic operational scenarios over time. Three absorbents—monoethanolamine (MEA), piperazine (PZ), and triethanolamine (TEA)—with distinct reaction kinetics were evaluated. The results indicated that under dry conditions, all absorbents achieve near-100 % CO 2 removal due to fast reaction kinetics relative to gas flow. However, under wetted conditions (20 %–60 %), absorbent type significantly influenced performance, with PZ (the fastest-reacting) removing up to 15 % of CO 2 at the maximum gas velocity (3.3 m/s), compared to just 5 % for TEA (the slowest-reacting) at 60 % wetting, while at 20 % wetting, the removal efficiencies were 51 % for PZ and 38 % for TEA. Furthermore, we modeled long-term performance decline due to membrane aging and wetting, providing novel insights for industrial applications. This work advances sustainable gas separation technologies by elucidating the interplay of wettability, absorbent kinetics, and temporal dynamics, and by addressing key gaps in previous research.