Nanostructured and recyclable palladium catalysts for hydrogenation of nitroarenes

This work reported the preparation of nanostructured palladium (Pd)-based catalysts that consisted of a magnetic core covered by a layer of functionalized mesoporous silica with Pd nanoparticles grown in situ within the porous channels (Fe3O4@mSiO2-Pd). The optimum Fe3O4@mSiO2-Pd with fine size and uniformly dispersed Pd nanoparticles was obtained on the amino (-NH2) functionalized magnetic mesoporous silica support with Na2PdCl4 as the Pd source. The performance of the synthesized Fe3O4@mSiO2-Pd was evaluated in the catalytic reduction of nitroarenes in aqueous solution with H2(g) as a reducing agent under ambient pressure and temperature. Compared with commercial Pd/SiO2, Fe3O4@mSiO2-Pd exhibited significantly improved reactivity in the reduction of various nitroarenes, which were completely reduced to the corresponding aminoarenes. The enhanced performance of Fe3O4@mSiO2-Pd may be attributed to the formation of small and well dispersed Pd nanoparticles within the confined support and the enhanced accessibility of reactive Pd sites within the mesoporous structure. Furthermore, the Fe3O4@mSiO2-Pd catalyst also showed excellent reusability and could be easily collected by an external magnetic field. Results suggested that the synthesized Fe3O4@mSiO2-Pd can be an effective and sustainable catalyst for hydrogenation of nitro-containing compounds.