Ion-Exchange Fabrication of Hierarchical Al-MOF-Based Resin Catalysts for the Tandem Reaction

Metal-organic framework (MOF)-supported macroscale resin catalysts, IRA900(xOH)-MIL-101(Al)-NH₂ (x means the concentration of NaOH), with spatially isolated antagonistic acid-base active sites were successfully synthesized through a novel strategy by ion exchange and in situ solvothermal methods. The hierarchical pore system of the as-prepared catalysts effectively promotes the mass transfer and contacts with catalytic active centers during the organic reactions. Therefore, the environmentally friendly catalysts exhibit excellent superior activity and stability in one-pot deacetalization-Knoevenagel condensation reaction, and the yield by optimal IRA900(0.2OH)-MIL-101(Al)-NH₂ reaches close to 99% after 5 h at 110 °C. Thanks to the millimeter-sized resin carrier and robust sphere morphology, the recycling of the as-prepared catalysts only requires natural sedimentation. This work presents an effective strategy to build low-toxic acid-base catalysts by combining the advantages of ion-exchange resins and functionalized MOF materials.