Two novel magnetic mesoporous core-shell nanocomposites Ni@mSiO2 and Ni-N2H4@mSiO2 were prepared by a surfactant-templating method. Nickel nanoparticles were first obtained from nickel nitrate or nickel chloride by thermodecomposition and hydrazine hydrate reduction

then covered by a mesoporous shell

and finally by sinteration and hydrogen reduction. As a comparison

Ni/mSiO2 carrier supporting catalyst was prepared by the traditional coprecipitation method. The core-shell nanocomposite of nickel nanoparticle core and mesoporous silica shell was characterized by transmission electron microscopy

X-ray diffraction and nitrogen adsorption-desorption. Temperature programmed H2 reduction indicated that NiO in these catalysts were mainly present in bulk phase and some small NiO particles in Ni-N2H4@mSiO2 were easily reduced. H2-chemsorption results demonstrated that Ni/mSiO2 had more active sites but lower TOF value compared to core-shell Ni@mSiO2 and Ni-N2H4@mSiO2 catalysts. Both Ni@mSiO2 and Ni-N2H4@mSiO2 showed higher activity and better selectivity than Ni/mSiO2 in selective hydrogenation of cinnamyl aldehyde to hydrocinnamaldehyde

with over 90% yield of hydrocinnamaldehyde. Due to high magnetic saturation value of Ni-N2H4@mSiO2

it can be easily recycled for reuse by an external magnetic field. Notably

Ni-N2H4@mSiO2 showed better stability in hydrogenation.