Methylamine Separations Enabled by Cooperative Ligand Insertion in Copper–Carboxylate Metal–Organic Frameworks
Year: 2024
Type: article
Abstract: High Resolution Image Download MS PowerPoint Slide Monomethylamine (NH 2 CH 3 ), dimethylamine (NH(CH 3 ) 2 ), and trimethylamine (N(CH 3 ) 3 ) are important chemical feedstocks that are produced industrially as an azeotropic mixture and must be separated using an energy-intensive thermal distillation. While solid adsorbents have been proposed as alternatives to distillation for separating various industrial gas mixtures, methylamine separations remain largely unexplored in this context. Here, we investigate two isoreticular frameworks Cu(cyhdc) (cyhdc 2– = trans -1,4-cyclohexanedicarboxylate) and Cu(bdc) (bdc 2– = 1,4-benzenedicarboxylate) as prospective candidates for this challenging separation, motivated by the recent discovery that Cu(cyhdc) reversibly captures ammonia through a unique framework-to-coordination polymer phase change. Through a combination of gas adsorption and powder X-ray diffraction analyses, we find that Cu(cyhdc) and Cu(bdc) reversibly bind large quantities of mono- and dimethylamine through framework-to-coordination polymer phase change mechanisms, although both frameworks adsorb only moderate amounts of trimethylamine via physisorption. Single-crystal X-ray diffraction analysis of select mono- and dimethylamine containing phases suggests that the number of hydrogen bond donors available and the linker donor strength are key factors influencing amine uptake. Finally, investigation of the tricomponent adsorption behavior of both materials reveals that Cu(cyhdc) is selective for the capture of monomethylamine from a range of mono-, di-, and trimethylamine mixtures.
DOI: 10.1021/jacs.4c06718
Language: English
Subfield: Inorganic Chemistry
Field: Chemistry
Domain: Physical Sciences
Open Access status: hybrid
Estimated APC paid: $4,500
Funder: Basic Energy Sciences
Award: G2759181536
OpenAlex ID: W4401642173