Non-crystalline surface-modified hollow nanospheres of silica (HNS): Synthesis, characterization and catalytic application

Non-crystalline surface-modified hollow nanospheres of silica (HNS) with different amine groups were synthesized by the co-condensation under neutral conditions. The obtained materials were characterized by N2 adsorption–desorption isotherms, Fourier-transform infrared spectroscopy (FTIR), transmission electron micrographs (TEM), scanning electron micrographs (SEM), back titration, elemental analysis and thermogravimetric analysis (TGA). The effect of organoamine type, amine density, and the presence of silanol groups on the catalytic activity was investigated. The capping of silanols with trimethylsilyl groups resulted in a reduction in catalytic activity, indicating the existence of cooperative effect between amine and silanol in the condensation reaction.