Hybrid ceria and chitosan supported nickel nanoparticles: A recyclable nanocatalytic system in the reduction of nitroarenes and the synthesis of benzopyran derivatives in green solvent

Abstract

Abstract Mesoporous, highly temperature resistant, magnetically separable, bimetallic, and organic‐based photoluminescent nanocatalyst has been prepared. Chitosan can act efficiently as a support material for preparing nanocatalysts. Hybrid ceria, that is, iron‐doped‐cerium oxide (Fe@CeO 2 ), was prepared via coprecipitation method. Chitosan–iron‐doped‐ceria nanocomposite was prepared and kept in a solution of NiCl 2 to adsorb Ni 2+ ions, which were then reduced with NaBH 4 to accumulate nickel nanoparticles. The characterization of nanocatalyst was performed using different techniques such as X‐ray diffraction (XRD), field emission scanning electron microscopy (FE‐SEM), high‐resolution transmission electron microscope (HR‐TEM), energy dispersive X‐ray spectra (EDX), Brunauer–Emmett–Teller (BET), X‐ray photoelectron spectroscopy (XPS), and thermogravimetric analysis (TGA) analysis. The catalyst was found to have a very small size about 2–3 nm and having a large surface area of about 121 m 2 g −1 , which was stable up to 800°C. It was also found to be photoluminescent. The catalyst thus prepared is useful for the reduction of nitroarenes, which is a toxic compound that is often found as a pollutant in the environment, to anilines, key intermediates for the fine chemical, agrochemical, and pharmaceutical industries. Also, nanocatalyst was used for the synthesis of various substituted tetrahydrobenzo[ b ]pyrans, which is an essential structural component in various natural products, in good to excellent yields.