Materials Chemistry and Physics, Vol.213, 472-481, 2018
Cyclohexene oxidation catalyzed by flower-like core-shell Fe3O4@Au/metal organic frameworks nanocomposite
In this study, Fe3O4@Au/metal-organic frameworks (Fe3O4@Au/MOF) nanocomposite with flower-like core-shell structure was successfully synthesized via a hydrothermal route. The as-prepared catalyst was characterized using different techniques such as FT-IR, XRD, TEM, EDX, VSM, TGA, BET, and ICP. This nanocomposite exhibited an excellent catalytic performance in selective oxidation of cyclohexene to 2-cyclohexene-1-one by using molecular oxygen as green oxidant. The influence of reaction conditions including, pressure of molecular oxygen, temperature, time, solvent, and amount of catalyst on conversion and selectivity of products were evaluated. The activation energy (E-a) of the reaction was calculated from the Arrhenius plot, and estimated to be 15.296 kJ mol(-1). The reaction mechanism and the effect of solvatochromic parameters on conversion of cyclohexene and distribution of products were studied in details. The polarity (E-T(N)), and hydrogen-bond acceptor (beta) ability of solvents were effective on conversion and rate constant value. The catalyst was easily separated from reaction media by using an external magnet, and reused for at least four catalytic runs without losing its catalytic activity. (C) 2018 Elsevier B.V. All rights reserved.
Keywords:Flower-like;Core-shell nanostructure;Metal-organic frameworks (MOF);Cyclohexene oxidation;Reaction kinetics and mechanism