Synthesis of Pd(0) Nanoparticles in TiO2-SiO2 Xerogel

摘要

Pd/TiO2-SiO2 xerogels containing 0.15-0.75 wt % palladium are prepared from Pd(NO3)(2) center dot 2H(2)O solutions in a mixture of tetrabutoxytitanium (TBT) and tetraethoxysilane (TEOS) in a desiccator under acetic acid-water vapors in the batch mode at 20 degrees C followed by drying and calcination of the material at 850 degrees C. IR spectroscopy showed that the presence of Pd(NO3)(2) center dot 2H(2)O has no effect on the amount of newly formed Ti-O-Si bonds in the double oxide TiO2-SiO2 over the range of salt concentrations studied. X-ray powder diffraction showed that palladium present in the xerogel calcined at 850 degrees C is in the form of Pd(0) nanoparticles. The electron-microscopic morphology study showed that the items prepared (Pd(0) nanoparticles) had near-spherical shapes; their sizes fell in the range 20-230 nm. A means for varying Pd(0) nanoparticle size in the material is to vary the palladium(II) salt concentration at the dissolution stage.