Sol-Gel Synthesis, Characterization and Catalytic Activity of Pd Supported on Silica and Siloxane-Modified Silica

Abstract

Palladium supported on silica, Pd-SiO₂, and on siloxanemodified
silica, Pd-(CH₃)₂SiO·SiO₂, were synthesized by sol-gel
method. They were characterized by infrared spectroscopy X-ray
diffraction spectrometry, magnetic susceptibility and BET surface
area measurements. XRD confirmed that metallic Pd on the
siloxane-modifIed silica and on silica supports adopted face.
centered cubic structure. IR data of the modified system indIcated
that the intensity of hydroxyl stretching band due to silanol moiety
and water was dramatically decreased, and the methyl group is
structurally intact. The BET surface area measurements showed that
the surface area of the modifIed silica system is smaller than that
of the silica system. In the liquid-phase hydrogenation of
phenylacetylene over Pd/SiO₂ and Pd/(CH₃)₂SiO₂·SiO₂ systems,
Pd/SiO₂ catalysts exhibited higher catalytic actiivity than the
modified silica catalysts.