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Updated: Sep 11, 2026

Electrophoretic Crystallization of Ultrathin High-performance Metal-organic Framework Membranes
Published on: August 16, 2018
Triazine Crosslinking Enables Nitrogen-Enriched Carbon Molecular Sieve Membranes for Precision 1,3-Butadiene/n-Butane
Fangxu Fan1, Zeyuan Gao1, Tianyou Li1
1State Key Laboratory of Fine Chemicals, Frontier Science Center For Smart Materials, School of Chemical Engineering, Dalian University of Technology, Dalian, Liaoning, China.
Abstract:
Membrane separation provides an energy-efficient route for separating 1,3-butadiene (C4H6) from C4 hydrocarbon mixtures, but limited permeability and selectivity remain key barriers. Here, nitrogen-enriched carbon molecular sieve (CMS) membranes were fabricated from triazine-crosslinked fluorene-based copolyimide precursors. Pendant carboxyl sites enabled triazine crosslinking and anchored nitrogen-rich moieties within the precursor matrix. During pyrolysis, pre-dispersed triazine units carbonized with the polymer backbone, contributing to the formation of pyridinic-N and pyrrolic-N active sites while narrowing ultramicropores to approximately 4.79 Å. The optimized CL-CMS membrane exhibited a C4H6 permeability of 4353.0 Barrer, a C4H6/n-C4H10 selectivity of 141.9, and a C4H6/i-C4H10 selectivity of 1817.2, surpassing current upper bounds. Mechanistic analysis revealed a synergistic interplay between nitrogen-enriched pore chemistry and tailored ultramicropore confinement: the former preferentially enhanced C4H6 affinity, while the latter dominated molecular discrimination through diffusion-controlled sieving, increasing sorption and diffusion selectivities by up to 35% and 97%, respectively. This work establishes triazine-crosslinking-assisted precursor design as a promising strategy to couple adsorption chemistry with ultramicropore architecture, highlighting its potential for highly selective C4 separation and polymer-grade C4H6 purification.
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