Synthesis, Characterization and Catalytic Properties of Monometal/SiO2 and Bimetal/SiO2 Hollow Spheres with Mesoporous Structure

Abstract

Monometallic M1(M[Formula: see text] Ni/Cu/Fe/Co) silicates and bimetallic Ni–M2(M[Formula: see text] Cu/Fe/Co) silicates hollow spheres with mesoporous structure and the controllable morphology have been synthesized successfully via one-step sacrificial template method under hydrothermal conditions. The catalysts were obtained by reducing the corresponding silicates in situ under the hydrogen atmosphere at a certain temperature. All the silicates and the catalysts M1/SiO2 and Ni–M2/SiO2 hollow spheres have been characterized by X-ray powder diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), Brunauer–Emmett–Teller (BET) and temperature-programmed reduction (TPR) thoroughly and systematically. The morphology and reaction conditions of bimetallic Ni–M2 silicates hollow spheres depend on the second metal M2, which has been verified by SEM, TEM and XRD. From the results, it can be concluded that bimetallic silicates possess better physical properties in favor of the catalytic activity. Bimetallic Ni–M2/SiO2 hollow spheres had higher catalytic property than the monometallic M1/SiO2 and the conversion of nitrobenzene could reach 100% within 3[Formula: see text]h using Ni–Cu/SiO2 and Ni–Fe/SiO2 hollow spheres as catalysts.