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Olefin/Paraffin Separation through Carbonized Membranes Derived from an Asymmetric Polyimide Hollow Fiber Membrane

1999; American Chemical Society; Volume: 38; Issue: 11 Linguagem: Inglês

10.1021/ie990209p

1520-5045

Ken‐ichi Okamoto, Shigeo Kawamura, Makoto Yoshino, Hidetoshi Kita, Yusei Hirayama, Nozomu Tanihara, Yoshihiro Kusuki,

Synthesis and properties of polymers

Carbonized hollow fiber membranes were prepared by pyrolyzing an asymmetric hollow fiber membrane of a polyimide from 3,3‘,4,4‘-biphenyltetracarboxylic dianhydride and aromatic diamines at temperatures of 500−700 °C under a nitrogen stream. The precursor membrane was treated in air at 400 °C for 0.5 h before the pyrolysis. This pretreatment was effective for improvement of gas permeance of the carbonized membranes. The carbonized membranes had an asymmetric structure with a skin layer of around 200 nm in thickness. They had the characteristics of larger permeance and lower permselectivity for inorganic gas pairs such as O2/N2, but this was rather preferable to the separation of olefin/paraffin. The membranes pyrolyzed at 600−630 °C displayed good stability and excellent performances of propylene/propane and 1,3-butadiene/n-butane separation based on the molecular sieving.