Recyclable Au/SiO-Shell/FeO-Core Catalyst for the Reduction of Nitro Aromatic Compounds in Aqueous Solution.

Highly stable gold nanoparticles immobilized on the surface of amine-functionalized nanocomposite microspheres possessing a magnetite (FeO) nanoparticle core and a silica (SiO) shell (Au/SiO-shell/FeO-core) were prepared. These gold nanocomposite catalysts were tested for 4-nitrophenol (4-NP) and 2-nitroaniline (2-NA) reduction in aqueous solution in the temperature range 293-323 K and in the presence of aqueous NaBH reducing agent. The magnetically recyclable gold catalyst showed high stability (∼3 months), efficient recyclability (up to 10 cycles), and high activity (∼100% conversion within 225 s, ∼700 ppm 4-NP or 2-NA).