Naphthalenediimide-containing metal-organic frameworks for mixed matrix membranes designed for CO2 separation

Naphthalenediimide-containing metal-organic frameworks for mixed matrix membranes designed for CO2 separation

• Autor
• Gabriela Oliveira
• Co-autores
• Sérgio Brochsztain , José Fernando Queiruga Rey
• Resumo

• According to the Intergovernmental Panel on Climate Change's (IPCC) sixth report of 2021, climate changes caused by human activitity are leading to more frequent and extreme weather events. These climate changes have been attributed mainly to an increase in the emissions of carbon dioxide (CO2) and other greenhouse gases (GHG). In this context, it is very important to find new materials for the capture and storage of CO2. These materials should perform gas separations, such as CO2/N2 in the exhaust of thermoelectric stations or CO2/CH4 in natural gas reservoirs, and should therefore display high selectivity and permeability for gas separation. One technology that has been considered for this purpose is the use of mixed matrix membranes (MMMs), which consist of a polymeric matrix impregnated with an inorganic filler, such as metal-organic frameworks (MOFs). MOFs are porous crystalline solids formed by nodes, which are metal cations, interconnected by bifunctional organic ligands, forming one-, two- or three-dimensional coordination networks. In the present work, we synthesized MOFs for MMMs, using 1,4,5,8-naphthalenediimides (NDIs) as the organic ligands. In 2008, the group of Joseph Hupp, from Northwestern University, Illinois, reported for the first time that a NDI-based MOF was efficient in the separation of CO2 from CH4. For that purpose, they employed N,N?-bis(4-pyridyl)-1,4,5,8-naphthalenediimide (DPNI), a NDI derivative substituted with basic pyridine ligands, and zinc as the cation. Herein, we present a novel NDI ligand, N,N'-bis(4-carboxyphenyl)-1,4,5,8-naphthalenediimide (CNDI), containing acidic carboxylic acid ligands. CNDI was synthesized by the reaction of 1,4,5,8-naphthalic dianhydride with 4-aminobenzoic acid, using molten imidazole as the solvent. Two types of MOFs were prepared using CNDI as the ligand, namely an IRMOF, employing Zn as the cation, and an UiO-type MOF, employing Zr as the cation. MOF syntheses were performed in an autoclave at 120 oC, using dimethylformamide as the solvent. The MOFs were characterized by X-ray diffraction, scanning electron microscopy, UV-visible spectroscopy and N2 adsorption isotherms. The CNDI-based UiO MOF showed higher crystallinity than the material prepared with Zn. The UiO MOF also presented mesoporosity, leading to the conclusion that can be a candidate to be used in the synthesis of MMMs.

• Palavras-chave
• CO2 capture, metal-organic frameworks, naphthalenediimides
• Modalidade
• Pôster
• Área Temática
• Materias Funcionais Avançados