Ethylene is widely used in the petrochemical industry. During the production of ethylene, acetylene is generated as a byproduct. This byproduct can poison catalysts and cause, for example, the termination of the polymerization of C₂H₄. Therefore, the removal of acetylene from ethylene is important. Research into porous materials for C₂H₂/C₂H₄ separation has been focused on metal-organic frameworks (MOFs). The use of porous organic frameworks (POFs) for this gas separation is still rare.

Hao Ren, Jia Liu, Jilin University, Changchun, China, and colleagues have synthesized a stable 2D crystalline polyimide porous organic framework called PAF-120. The POF was synthesized by an imidization of the linear naphthalene-1,4,5,8-tetracarboxylic dianhydride and the triangular 1,3,5-tris(4-aminophenyl) benzene. PAF-120 is thermally and chemically stable.

The researchers found that PAF-120 can achieve a good, selective separation of C₂H₂ from C₂H₄. PAF-120 also effectively separates CO₂ and N₂. At 298 K and 1 bar, the C₂H₂/C₂H₄ and CO₂/N₂ selectivities were calculated to be 4.1 and 68.7, respectively. The framework has the highest selectivity for C₂H₂/C₂H₄ separation among POFs under these conditions.

• Construction of a Stable Crystalline Polyimide Porous Organic Framework for C₂H₂/C₂H₄ and CO₂/N₂ Separation,
  Lingchang Jiang, Pengyuan Wang, Meiping Li, Panpan Zhang, Jialu Li, Jia Liu, Yanhang Ma, Hao Ren, Guangshan Zhu,
  Chem. Eur. J. 2019.
  https://doi.org/10.1002/chem.201900857