A highly efficient Pd/Fe 3 O 4 @C catalytic system has been developed for direct reductive amination of carbonyl compounds with nitroarenes in aqueous reaction medium. The catalyst was characterized by TEM, XRD, XPS and VSM. It was found that the catalyst showed a high activity for the one-pot direct reductive amination of aldehydes with nitroarenes in the presence of molecular hydrogen at mild temperature. Besides, the catalyst could be recovered in a facile manner from the reaction mixture and recycled six times without obvious loss in activity.
Graphical AbstractKeywords Core-shell Á Pd (0) Á One-pot direct reductive amination Á Aldehydes Á Nitroarenes
A new nanocatalyst has been synthesized by confining magnetic nickel nanoparticles within carbon nanotubes (CNTs) and characterized by XRD, TEM, Raman and VSM. The character of the nanocatalyst passivated with a gas mixture was that it can be stored safely in air below 150 C and needs no activation prior to use. In the catalytic test, a nickel oxide nanocatalyst confined inside the Multi-walled carbon nanotubes nanochannels (NiO/MWCNTs-in) was found to be a highly efficient and reusable catalyst for the reduction of various aromatic nitro compounds to various aromatic amines, the conversion and selectivity of which were almost up to 100% and exceed 80%. The prominent merit of the catalyst is that the overall formation rate of product inside the nanotubes exceeds that outside. Moreover, it is inexpensive, and could be prepared and scaled up easily. Besides, it can be simply separated from the reaction mixtures by an external magnetic field As a result of the possible confinement effect of CNTs, the employment of the CNTs channels as nanoreactors for catalysis may provide opportunities for the development of new heterogeneous catalysts.
a Herein, we describe a method to prepare hollow magnetic mesoporous spheres catalyst (Ag/γ-Fe2O3@meso-TiO2) . The core-shell strategy efficiently prevents the aggregation of Ag NPs in the high temperature calcination process and the leaching of Ag NPs for the catalytic reaction in a liquid phase. The catalyst is characterized by TEM, XRD, ICP-AES. Moreover, the catalyst exhibited improved activity for synthesis of β-enaminones, and it could be easily recovered by an external magnet from the reaction mixture and recycled five times without any significant loss in activity.
Here, we report a facile synthesis approach to obtain a Pd@hTiO 2 hollow mesoporous nanocomposite composed of tiny Pd nanoparticles cores encapsulated within hollow TiO 2 mesoporous shells. The core-shell strategy efficiently prevents the aggregation of Pd NPs (Pd nanoparticles) in the high temperature calcination process and the leaching of Pd NPs for the catalytic reaction in a liquid phase.The catalyst was characterized by transmission electron microscopy (TEM), X-ray powder diffraction (XRD), X-ray photoelectron spectroscopy (XPS), N 2 adsorption/desorption, elemental analysis and inductively coupled plasma atomic emission spectrometry (ICP-AES). The synthesized catalyst exhibited high catalytic activity in the reduction of p-nitrophenol with NaBH 4 aqueous solution at room temperature. Furthermore, Pd@hTiO 2 had an excellent recyclability, evidenced by being extensively reused for eight times without any substantial loss of activity.
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