Novel Cu-doped zeolitic imidazolate framework-8 membranes supported on copper foam for highly efficient catalytic wet peroxide oxidation of phenol

Abstract

Cu-doped zeolitic imidazolate framework-8 (ZIF-8) membranes supported on three-dimensional copper foam were prepared for the first time and used for the catalytic wet peroxide oxidation of phenol in a fixed bed reactor. The properties of the new porous composite materials were studied by scanning electron microscope, energy-dispersive spectroscopy, Brunauer-Emmett-Teller surface area analysis, X-ray diffraction, thermal gravimetric analysis, Fourier-transform infrared, and X-ray photoelectron spectroscopy. The ZIF-8 membrane doped with 5% copper exhibited the best catalytic performance (the removal efficiency of phenol and H2O2 reached 100% and 95%, respectively). Reusability and stability experiments showed that a consistent complete phenol conversion and high H2O2 conversions of more than 94% were achieved using the 5% Cu-doped ZIF-8 membrane. The effects of reaction temperature, feed flow rate, and catalyst bed height on the catalytic performance were investigated to obtain the optimal reaction conditions. The material has the more economical characteristics of short reaction time, low metal loading, continuous operation, easy recycling, and good stability. The kinetics of the catalytic reaction of the Cu-doped ZIF-8 membrane were analyzed using the Power-rate Law Kinetic model. The experimental results show that the reaction is a first-order reaction, and the activation energy (Ea) of the catalyzed oxidation reaction is 66.4 kJ/mol. The initial oxidation rate equation (−rA0 = 3.24 × 108e−66400/RT CA) was obtained for Cu-doped ZIF-8 membrane–catalyzed phenol degradation.