Facile synthesis of an IRMOF-3 membrane on porous Al2O3 substrate via a sonochemical route

• IRMOF-3 membrane on Al2O3 disc was prepared by sonochemical method.
• Properties were compared with those prepared by microwave heating.
• IRMOF-3 powders were synthesized independently for membrane process optimization.
• IRMOF-3 membrane enabled easy catalyst separation in Knoevenagel reaction.

A densely-packed IRMOF-3 membrane (S-IRMOF-3(Mem)), ∼55 μm in thickness, on an Al2O3 disc support was prepared via a sonochemical synthesis route, and the optimal fabrication conditions were established. Bare IRMOF-3 particles (S-IRMOF-3(p)) were synthesized independently to analyze the contribution of the Al2O3 support. The overall physicochemical properties of the IRMOF-3 products produced via the sonochemical route were superior to those prepared by microwave heating. The IRMOF-3 materials produced were characterized by XRD, SEM, EDS-mapping, and N2 adsorption–desorption measurements. S-IRMOF-3(p) exhibited satisfactory CO2 adsorption capacities (54 mg/g at 298 K/1 bar; 732 mg/g at 298 K/20 bar) and CO2/N2 selectivity (18 at 298 K/1 bar). Both S-IRMOF-3(Mem) and S-IRMOF-3(p) were assessed as a catalyst for a liquid phase Knoevenagel condensation reaction between benzaldehyde and ethyl cyanoacetate. S-IRMOF-3(Mem) and S-IRMOF-3(p) showed comparable conversions (87–89%) with 100% selectivity after a 4 h reaction at 333 K. The heterogeneous nature of the catalyst was confirmed by a hot filtering experiment, and S-IRMOF-3(Mem) could be recovered easily after the reaction and be recycled several times with little change in product yield.

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