Carbon Molecular Sieve Membranes with Ultra‐Thin Selective Skin Layer by Pyrolysis of Porous Hollow Fibers

Abstract Translating carbon molecular sieve (CMS) membranes into highly scalable hollow fiber geometry with ultra‐thin selective layer (<1 µm) for gas separation remains as great challenge. The porous support layer of precursor hollow fiber membranes is prone to collapse during pyrolysis, which induces thick skin layer (15–50 µm) of CMS hollow fiber membranes. Here, a novel strategy is present to obtain an ultra‐thin selective skin layer by carbonization of hollow fiber membranes with porous skin. P84‐based defect‐free CMS hollow fiber membranes with ultra‐thin selective skin layer (0.9 µm) for gas separation are prepared without any coating or complex chemical pretreatment. Compared with the carbon membranes derived from defect‐free fibers, the H 2 permeance (93.9 GPU) of CMS membranes derived from the porous fibers increases ≈1353% with comparable selectivity of H 2 /CH 4 (143) and higher H 2 /N 2 (120). Furthermore, the porous fibers are pre‐aged near the T g in N 2 conditions before carbonization, and the H 2 permeance of the derived CMS hollow fiber membranes reached 147 GPU (increased 2180%). It is a new facile way to prepare CMS hollow fiber membranes with ultra‐thin selective layer by porous fibers, demonstrating its versatile potential in gas separation or organic liquids separation.