A scalable zinc-based coordination network for energy-efficient NF3/CF4 separation with unprecedented selectivity

Abstract

Nitrogen trifluoride (NF₃) and carbon tetrafluoride (CF₄) are critical gases in the semiconductor industry. However, their current lack of effective recycling and separation results in significant waste emissions, which are not only costly but also pose significant environmental challenges. Their separation remains a critical challenge due to their nearly identical physicochemical properties (Δbp <1 °C, similar polarizability). Here, we demonstrate that a zinc-based metal–organic framework (CALF-20) with precisely tuned 4.8 Å pores achieves exceptional NF₃/CF₄ separation through molecular sieving. At 298 K, this material exhibits a record-high NF₃/CF₄ adsorption ratio of 41.1, and a CF₄ purity of 99.5% can be achieved through breakthrough experiments. Structural characterization and computational studies reveal that the unique pore channel properties preferentially adsorb NF₃ (kinetic diameter: 4.5 Å) while effectively excluding CF₄ (4.8 Å). This advance enables cost-effective gas purification at $12.3 per kilogram, providing a practical solution for sustainable semiconductor manufacturing.