Preparation of defect-free hollow fiber membranes derived from PMDA-ODA polyimide for gas separation

• Published in: Chemical engineering research & design Vol. 179; pp. 154 - 161
• Main Authors: Chen, Mingyang, Yang, Rui, Li, Pei
• Format: Journal Article
• Language: English
• Published: Rugby Elsevier Ltd 01.03.2022; Elsevier Science Ltd
• Subjects: Carbon dioxide; Defect-free; Gas separation; Hollow fiber membranes; Hydrogen bonds; LiCl; Membrane separation; Phase inversion; Phase shift; Phase transitions; PMDA-ODA; Polymers; Selectivity; Defect-free; Hollow fiber membranes; PMDA-ODA; Gas separation; LiCl
• ISSN: 0263-8762; 1744-3563
• DOI: 10.1016/j.cherd.2022.01.017

•For the first time, defect-free PMDA-ODA hollow fiber gas separation membranes are prepared.•Fast spinning of PMDA-ODA hollow fiber is realized by adding LiCl.•A skin layer of 1 μm is obtained after thermal imidization. Since PMDA-ODA polyimide is insoluble, its soluble precursor PMDA-ODA poly (amic acid) (PAA) is used to prepare hollow fiber membranes (HFMs). Due to the existence of –CO–NH– and –COOH groups, PAA is subject to form hydrogen bonds with water and consequently leads to a very slow phase inversion rate during the non-solvent induced phase inversion process. Therefore, the hollow fiber spinning has to be carried out with a low take-up speed that limits the productivity. In this paper, we increased the take-up speed of PAA hollow fiber to 60 m/min by simply adding LiCl into polymer dope. Moreover, an integrally skinned defect-free PMDA-ODA hollow fiber membrane was obtained at the high take-up speed where the gas permeances were 6.8 ± 0.7, 2.2 ± 0.2, 0.4 ± 0.04 and 0.07 ± 0.01 GPU for H2, CO2, O2 and N2, respectively, with an ideal selectivity of 3.1 ± 0.3, 31 ± 3.0 and 5.7 ± 0.6 for H2/CO2, CO2/N2 and O2/N2, respectively. These results indicated a dense PMDA-ODA layer of 1 μm. To our best knowledge, this is the first time that a defect-free hollow fiber membrane for gas separation is prepared based on PMDA-ODA.