One-pot construction of ionic liquid-functionalized MOF material as the catalyst for CO₂ cycloaddition under atmospheric pressure

Carboxylic ionic liquid 1-propionic acid-3-methylimidazolium chloride (CFIL) was immobilized in a metal-organic framework (MOF) material NH₂-MIL-101 in one-pot by the in-situ assembly method; as a heterogeneous catalyst with multiple active sites, the catalytic performance of NH₂-FMOF-CFIL in the cycloaddition of CO₂ with epichlorohydrin (ECH) to synthesize chloropropylene carbonate (CPC) was investigated. The immobilized of CFIL in NH₂-MIL-101 was proved by Fourier transform infrared spectroscopy (FT-IR) and elemental analysis, while the powder X-ray diffraction (PXRD), scanning electron microscopy (SEM) and N₂ adsorption-desorption measurements demonstrated that CFIL neither damages the crystal structure nor blocks the pore of NH₂-MIL-101, but induce the formation of mesopores. The catalytic reaction results reveal that there is a catalytic synergy between imidazole N and Cl⁻ on CFIL and Cr³⁺ and amino group on MOF, which endow the NH₂-FMOF-CFIL composite excellent catalytic performance in the cycloaddition of CO₂ with ECH; under mild conditions, viz., 0.1 MPa CO₂, 25–70 ℃ and without using any solvent and cocatalyst, the CPC yield reaches 99% after reaction for 24 h. Moreover, the crystal structure and high activity of the NH₂-FMOF-CFIL catalyst are well preserved even after reuse for 5 cycles.