The synthesis of amide bond by a simple one-step method to connect ionic liquid and MIL-101-NH2 firmly for efficient CO2 cycloaddition

• Published in: Separation and purification technology 2024-09, Vol.344, p.127061, Article 127061
• Main Authors: Wang, Huidong, Gao, Ziyu, Sun, Jianmin
• Format: Article
• Language: English
• Subjects: Amide bond connection; CO2 cycloaddition reaction; Cyclic carbonate; Ionic liquid grafting; Metal-organic framework; One-step synthesis
• ISSN: 1383-5866; 1873-3794
• DOI: 10.1016/j.seppur.2024.127061

[Display omitted] •The imidazolyl ionic liquid was grafted to MIL-101-NH2 with amide bond connection through a simple solvothermal method.•The porous structure and high BET surface area made 1-C-3-M@MIL-101-NH2 possessing good affinity to CO2.•The catalyst showed efficient catalytic activity for the CO2-eoixide cycloaddition under cocatalyst-free and mild conditions.•As a heterogeneous catalyst, 1-C-3-M@MIL-101-NH2 had good thermal and cycle stability. Finding robust combination modes between ionic liquids and MOFs is still a challenge. In this work, using a simple one step-synthesis method, the ionic liquid was grafted onto MOF without any additives, and the binding mode of the two was characterized by means of XPS, FT-IR, TGA, SEM etc. It was found that the carboxyl group in the ionic liquid bonded with the amino group in MOF to form an amide bond. Thus, a novel stable composite material MIL-101-NH2-1-carboxypropyl-3-methylimidazolium bromine (1-C-3-M@MIL-101-NH2) was synthesized. This composite employed as a catalyst for CO2 cycloaddition demonstrated excellent catalytic activity, achieving a target product PC (Propylene carbonate) yield of 91.7 % under the conditions of 80 °C, 1.0 MPa, and a reaction time of 4 h, without the addition of any co-catalysts or solvents. The good catalytic activity was benefit from the synergistic effect of Lewis acidic Cr centers and nucleophilic Br-, as well as the high specific surface area and good CO2 affinity of 1-C-3-M@MIL-101-NH2. In addition, owing to this robust bonding configuration, the catalyst can be recycled up to five times without losing activity. It is a potential catalyst for CO2 capture and conversion.