Ionic liquid – grafted mesoporous silica exhibiting reverse selectivity for ethane/ethylene separation

• Published in: Separation and purification technology Vol. 323; p. 124324
• Main Authors: Anwar, Fahmi, Suresh Kumar Reddy, K, Mathai Varghese, Anish, Khaleel, Maryam, Wang, Kean, Karanikolos, Georgios N.
• Format: Journal Article
• Language: English
• Published: Elsevier B.V 15.10.2023
• Subjects: Adsorption; Ethane; Ethylene; Ionic liquid; MCM-41; Reverse selectivity; Reverse selectivity; MCM-41; Adsorption; Ethane; Ethylene; Ionic liquid
• ISSN: 1383-5866; 1873-3794
• DOI: 10.1016/j.seppur.2023.124324

[Display omitted] •Ionic liquid-grafted silica exhibiting reverse selectivity for ethane/ethylene separation.•Ionic liquids in situ synthesized onto the mesoporous silica’s pre-silanized surface.•IL loading and type of anion and cation systematically investigated.•Low isosteric heat of adsorption, indicatively 12 kJ/mol for ethane.•Breakthrough C2H4 productivity of 1.2 mmol/g with an C2H6/C2H4 selectivity of 2.4.•Stable performance for multiple adsorption–desorption PSA and breakthrough cycles. Development of paraffin-selective adsorbents for the separation of ethane/ethylene mixtures, as an alternative technology to the energy-intensive cryogenic distillation, is challenging. Herein, we report surface-functionalized mesoporous silica adsorbents exhibiting reverse selectivity prepared by controlled in-situ synthesis of paraffin-selective ionic liquids (ILs) onto the pre-silanized surface of MCM-41 mesoporous silica. The surface modification switched the selectivity of the adsorbents from being inherently olefin-selective to becoming paraffin-selective, due to the enhanced van der Waal’s interactions between the grafted IL functionalities and the ethane molecules. A range of silica-based adsorbents functionalized with ILs of different loadings and anion and cation types were synthesized, characterized and investigated for their ethane/ethylene adsorption behavior. In addition to reversing the selectivity yielding values of up to 3.4 for ethane over ethylene, the adsorbents exhibited low isosteric heat of adsorption, indicatively 12 kJ/mol for ethane, while their performance was stable upon pressure swing adsorption and breakthrough cyclic testing. Dynamic packed bed experiments with ethane/ethylene mixtures demonstrated a breakthrough ethylene productivity of up to 1.2 mmol/g with a breakthrough selectivity of 2.4.