Benchmark Performance of One-Step Ethylene Separation: From Optimized Crystal Synthesis to Quantitative Mixture...

Area of Science:

• Materials Science
• Chemical Engineering
• Separation Science

Background:

• Adsorption is a promising technique for chemical separations, particularly for ethylene (C₂H₄) and ethane (C₂H₆).
• The field requires benchmark adsorbents and standardized quantitative evaluation protocols for reliable performance assessment.
• Existing C₂H₆-selective adsorbents face challenges in achieving high purity and productivity in one-step separations.

Purpose of the Study:

• To develop an amorphous-recrystallization method for controlling the crystal size and morphology of the MAF-49 adsorbent.
• To optimize crystal size for enhanced one-step separation of C₂H₄ from C₂H₆ mixtures.
• To establish quantitative evaluation protocols for gas mixture adsorption and separation processes.

Main Methods:

• An amorphous-recrystallization technique was employed to tune the crystal size of MAF-49.
• Column breakthrough experiments were conducted, switching from outlet concentration to outlet flow-rate mode.
• The RUPTURA simulation code was modified for quantitative parameter prediction.

Main Results:

• The optimal crystal size of MAF-49 yielded negligible C₂H₄ kinetic selectivity, achieving a record productivity of 3.1 mmol cm^-3 for C₂H₄ purification.
• Larger crystals showed increased C₂H₄ kinetic selectivity, negatively impacting purification performance and potentially leading to apparent C₂H₄ selectivity.
• The modified evaluation protocol enabled accurate prediction of purification productivity, adsorption capacity, and selectivity.

Conclusions:

• Controlling adsorbent crystal size is critical for optimizing separation performance and productivity.
• The developed amorphous-recrystallization method and quantitative evaluation protocol offer a pathway for advancing adsorbent-based separations.
• This study provides a benchmark for evaluating C₂H₄/C₂H₆ separation using adsorbents.