Synthesis of Cost-effective Trimetallic Oxide Nanocatalysts for the Reduction of Nitroarenes in Presence of NaBH4 in an Aqueous Medium

Abstract

Background: To prevent the environmental pollution, the release of the carcinogenic reagents like nitroarenes, especially nitrobenzene must be reduced or to find a way to convert these hazardous materials into less harmful material. For the reduction of nitroarenes, various types of catalysts such as metal nanoparticles (mainly coinage and group VIII) and platinum group metals were used. The chemo/homo selectivity of the reduction of nitroarenes was tested mainly in an organic solvent medium. Method: Trimetallic oxide nanocatalysts were prepared chemically and characterized via Thermogravimetric analysis (TGA), X-ray diffraction (XRD), Fourier transform infrared spectroscopy FTIR), Scanning electron microscope (SEM) and solid UV studies. A series of nitroarenes were subjected to get their amine analogues using the NaBH4 in an aqueous medium using the synthesized catalysts. The completion of the reduction process was confirmed by the spectroscopic analysis. Results: The average crystallite of the trimetallic oxide nanocatalysts was found to be 14-32nm. The reductions were selective (homo/chemo) and kinetics followed the Lindemann-Hinshelwood pseudofirst order kinetics with the rate constant in the order of 10-3 s-1. Hydroxylamine intermediate was found to be formed in the reduction procedure. Conclusion: The catalysts showed promising for the selectivity (homo/chemo). The reduction processes were less time consuming e.g. nitrobenzene took 10 mins and a series of nitroanilines required 35-40 s for the reduction. In short, the trimetallic nano-oxide catalysts possess fast reaction process, cost-effective, easy to handle, reusable and hence could be promising for industrial waste treatment.