Fluorinated porous organic frameworks for C₂F₆/CF₄ gases separation

As an indispensable raw material for silicon-based semiconductor industry, carbon tetrafluoride (CF₄) is widely used as plasma etching and cleaning gas in the manufacture of semiconductors. How to efficiently remove the C₂F₆ impurity during the CF₄ production process is a challenging task as semiconductor industry requires high-purity CF₄ gas. Herein, two fluorine-functionalized porous organic frameworks (F-POFs) named SPPOF-4F and SPPOF-8F were synthesized and used for separation of C₂F₆/CF₄ gases. Single-component gas adsorption experiments and ideal adsorbed solution theory (IAST) calculations indicate that two porous organic frameworks can selectively adsorb C₂F₆ from C₂F₆/CF₄ mixture. Molecular simulations have further complemented these experimental findings by revealing F-induced host-guest interactions between F-POFs and C₂F₆ at a molecular level. Additionally, dynamic breakthrough experiments verified that the F-POFs can capture C₂F₆ in C₂F₆/CF₄ mixture at practical conditions. These results indicate that F-POFs have great potential for application in the separation and purification of CF₄ electronic special gases.