Room temperature complete reduction of nitroarenes over a novel Cu/SiO2@NiFe2O4 nano-catalyst in an aqueous medium - a kinetic and mechanistic study

摘要

The current investigation reports the preparation of a novel system, Cu/SiO2@NiFe2O4, as characterised by XRD, XPS, IR, SEM-EDS, TEM, ICP-AES and VSM data. Its catalytic activity was explored in nitroarene reduction using 4-nitrophenol as the model substrate for studying the reaction kinetics. The studies revealed the rate constant of the reaction at room temperature to be 0.325 min(-1). Each test reaction here contained only 10.6 mu g of copper, wherein the activity factor was 0.511 s(-1) mg(-1), which is by far the highest for any non-noble metal catalyst reported for this reaction. Moreover, the energy of activation of the reaction was found to be 30.4 kJ mol(-1), which falls in the lower range of the average E-act reported in the literature for the reaction under study. Further insights on the reaction pathway indicated that the reaction followed a direct route for nitro-reduction via the formation of a nitroso derivative. Overall, we present herein an economical, efficient and environmentally benign methodology for nitroarene reduction using the designed catalyst.