Enhanced azeotropic C₂ClF₅/C₃F₈ separation by TMA⁺ exchanged MFI zeolites for ultrapure fluorine electronic gas

Abstract

The demand for the azeotropic C2ClF5/C3F8 separation continues to rise owing to the significance of ultrapure fluoride gases for the electronic industry. With a boiling point differential of 1.1 K, separating an azeotropic mixture of C2ClF5/C3F8 through sorption‐based processes under ambient conditions is a preferable alternative to the current energy‐intensive cryogenic separation method. Here, we report the highly efficient C2ClF5/C3F8 adsorption separation in quaternary alkylammonium ions modified MFI type zeolites with interlaced channels which provide a cooperative effect conferred by specific interaction sites and optimal pore size. A path‐regulatory mechanism was proposed, whereby TMA+ cations located at intersections resembling “train turnouts” force gas molecules to switch traffic channels to confined sinusoidal channels affecting the C2ClF5/C3F8 recognition sites and diffusion behavior. Molecular simulations were conducted to reveal the separation mechanism, and the breakthrough experiment validated the effectiveness of this adsorbent at 298 K outperforming conventional adsorbents for the challenging azeotropic separation.