Synthesis, characterisation, and catalytic properties of halloysite-supported metal nanoparticles

A facile synthetic method is reported for the immobilisation of metal nanoparticles on halloysite, an aluminosilicate material with a unique nanotubular structure. A one-step colloidal synthesis was developed, from which nine different catalysts were prepared. The materials were tested in three different catalytic hydrogenations, and the halloysite-supported catalysts were found to outperform alumina- or silica-supported catalysts prepared in the same fashion. Electron microscopy showed that the activity was closely linked to the spatial distribution of the supported metal particles, which in turn affected the shapes of certain surface-associated peaks in the infrared and nuclear magnetic resonance spectra. From this data insight is gained into the nature of the interaction between metal nanoparticles and the surfaces of these support materials.