Magnetic Recyclable Nanocomposite Catalysts with Good Dispersibility and High Catalytic Activity

Nanocomposite catalysts containing both magnetite (Fe 3 O 4 ) and palladium (Pd) nanoparticles with magnetic separation and recyclability were successfully fabricated via polymer encapsulation and then silica coating and applied for catalytic hydrogenation of 4-nitrophenol. Fe 3 O 4 nanoparticles were used as not only the prerequisite of magnetic separation but also the supports to prevent the aggregation of Pd nanoparticles at high temperature. Moreover, the surfactants and polymer supports on the particle surface were removed by calcination, and thus the catalysis centers (Pd nanoparticles) were totally exposed to the reactants, which is preferable for a good catalysis efficacy. The results of catalytic hydrogenation of 4-nitrophenol demonstrated that the catalytic activity of these as-prepared nanocomposite catalysts were well maintained even after 10 repeated cycles. Unlike the noble metal nanoparticle decorated large magnetic nanosphere with residual magnetism, these as-prepared nanocomposites based on superparamagnetic nanoparticles possess many advantages including high catalytic activity, convenient magnetic separation, good dispersibility, high water stability, and excellent recyclability.