"Two-in-One" Anion Engineering Strategy for One-Step Ethylene Purification From a Ternary Mixture

Area of Science:

• Materials Science
• Chemical Engineering
• Separation Science

Background:

• Purifying ethylene (C₂H₄) from acetylene (C₂H₂) and carbon dioxide (CO₂) is an industrial challenge.
• Conventional methods struggle to balance adsorption capacity and selectivity for efficient gas separation.

Purpose of the Study:

• To develop an innovative anion engineering strategy for enhanced C₂H₄ purification.
• To improve CO₂ capture and C₂H₄ selectivity in multi-component gas mixtures.

Main Methods:

• Implemented a "two-in-one" anion engineering strategy, substituting SiF₆^2- with ZrF₆^2-.
• Utilized material characterization, gas adsorption isotherms, ideal adsorbed solution theory (IAST) calculations, and dynamic breakthrough experiments.
• Performed theoretical calculations to understand the interaction mechanisms.

Main Results:

• The modified material, ZrFSIX‑1‑Cu‑(CH₃)₂, showed significantly enhanced CO₂ uptake (87.3 cm³/g) compared to the original (35.3 cm³/g).
• Adsorption selectivity shifted from C₂H₄-selective to CO₂-selective, with CO₂/C₂H₄ selectivity increasing from 0.59 to 1.66.
• Demonstrated exceptional separation performance for a C₂H₂/CO₂/C₂H₄ mixture in dynamic breakthrough experiments.

Conclusions:

• The ZrF₆^2- anion engineering strategy effectively enhances CO₂ capture and ethylene purification.
• Highly electronegative fluorine atoms and pore structure modifications contribute to selective CO₂ adsorption.
• This approach offers a new paradigm for designing materials for purifying ethylene from complex industrial gas streams.