Complex Olefin Separations by Coordinated Silver(I) Containing Ionic Liquid Stationary Phases Using Comprehensive...

Area of Science:

• Chemical Engineering
• Analytical Chemistry
• Materials Science

Background:

• Olefins are key industrial intermediates, necessitating selective separation methods.
• Silver(I) ionic liquids (ILs) offer tunable π-complexation for olefin separation.
• Comprehensive two-dimensional gas chromatography (GC × GC) requires advanced stationary phases for complex mixtures.

Purpose of the Study:

• To evaluate coordinated silver(I)/IL mixtures as GC × GC stationary phases.
• To examine the chromatographic selectivity of these phases for olefins, diolefins, and paraffins.
• To investigate factors influencing silver-olefin interactions and separation performance.

Main Methods:

• Preparation and characterization of six coordinated [Ag+]/IL mixtures.
• Application of these mixtures as second-dimension stationary phases in GC × GC.
• Analysis of chromatographic selectivity and resolution for various hydrocarbon classes.
• Calculation of free energy of solvation (ΔG) for diolefins.

Main Results:

• Coordinated [Ag+]/IL phases demonstrated enhanced selectivity and resolution for olefin separations.
• The [Ag+(Py)2][NTf2-]/[BMIM+][NTf2-] mixture achieved high resolution between n-octane and trans-2-octene.
• 1,5-hexadiene showed a more favorable ΔG than longer-chain diolefins, indicating chelation effects.
• Olefin structure and chelation were found to be more critical than carbon chain length in Ag+-olefin interactions.

Conclusions:

• Tailoring the silver complex and IL component allows fine-tuning of olefin selectivity.
• These silver(I)/IL systems are effective for complex hydrocarbon separations using GC × GC.
• The study provides insights into optimizing separation media for industrial olefin applications.