Magnetically Recyclable Cu-BTC@SiO₂@Fe₃O₄Catalysts and Their Catalytic Performance for the Pechmann Reaction

Abstract

Novel magnetic Cu-BTC@SiO2@Fe3O4 catalysts were synthesized by encapsulating magnetic SiO2@Fe3O4 nanoparticles into Cu-BTC through an in situ method. The structure of the catalysts was characterized by transmission electron microscopy (TEM), scanning electron microscopy (SEM), X-ray diffraction (XRD), Fourier transform infrared (FT-IR) spectroscopy, a vibration sample magnetometer (VSM), N2 adsorption/desorption, and NH3-temperature programed desorption (NH3-TPD). The catalytic activity and recovery properties of the catalysts for the Pechmann reaction of 1-naphthol (NP) with ethyl acetoacetate (EAA) were evaluated. The results showed that the magnetic Cu-BTC@SiO2@Fe3O4 catalysts had the larger surface areas, suitable superparamagnetism, and good catalytic activity for Pechmann reaction. The conversion of 1-naphthol can reach ∼96%, and the selectivity of the production can reach ∼98% over 50.8% Cu-BTC@SiO2@Fe3O4 (MCC-10) catalyst under the reaction conditions of 130 °C and 24 h. After the reaction, the catalyst can be easily separated from the reaction mixture by an external magnet. The recovery catalyst can be reused for five times, and the conversion of 1-naphthol can be kept over 90%.