Scaling of HKUST-1 metal–organic framework polymer with catalytic and adsorption properties

Metal–organic frameworks of HKUST-1 {[Cu²⁺₂(BTC)^3-₂)(Solv)_x]×G_y}_n (CuBTC;Solv.-solvent in framework; G-guest in voids) are composed of Cu²⁺ dimers linked by benzene-1,3,5-tricarboxylate (BTC). CuBTC exhibits cubic symmetry (sp.gr.Fm3m,Z=16), an ordered 3D pore structure, high specific surface area, thermal stability, adsorption capacity, and selectivity. The use of CuBTC is related to technological feasibility: CuBTC can be produced in required quantities with reduced cost and high performance characteristics, which became the motivation for this study.

Synthesis (reagents: Cu(NO₃)₂×3H₂O, H₃BTC; solvents: water, ethanol, DMF) was carried out using the solvothermal method (SA;t=130°C,t=8 h;n=1 gram-product weight) and express method in a water bath (WB/n;t=84°C,t=3 h;n=4 and 10grams) with thermal treatment (t=200°C, t=5 h) of WB/10 to open the active centers in the structure of dehydrated/desolvated WB/10D.

XRD, IR spectroscopy, SEM/EDX and BET show changes in the microstructure and morphology/habitus from a large number of octahedra (10–20 mm) and a small number of shapeless crystals in WB/4 to octahedra, intergrowths and twins (from 10 to 60 mm) in WB/10. A decrease in specific mesoporous surface areas from 893m²/g in SA to 810m²/g in WB/10 was revealed. A significantly smaller amount or even absence of G in WB/10D compared to WB/10 was found, and the compositions of WB/4 and WB/10 are similar.

Low-temperature adsorption activity for N₂ is higher for SA (~272cm³/g) compared to WB/10 (~258cm³/g); the conversion of allyl alcohol and hydrogen peroxide to glycidol is higher for WB/10D than for WB/10, but the selectivity of GD for HP is significantly higher for WB/10. This indicates different mechanisms of catalytic process due to changes in the nature of active centers.

Funding: Ministry of Science and Higher Education of the Russian Federation, grant number FSFZ-2024-0003.