Abstract: The morphology of supported metal nanoparticles on
TiO_2/silical gel (TSO) and photothermal synergism were
investigated for destruction of ethylene. During photocatalytic deposition of
metal nanopartilces, the effects of pH and light intensity on the morphology of
coated platinum, palladium, gold on TiO_2/silical gel were
studied. Moreover, these catalysts were characterized by TEM, UV-Vis DRS. The
pH of preparing solution have strong influence on dispersion, size and sites of
Pt, Pd and Au on TSO, which were controlled by the electrostatic binding of
HPtCl_6^-, AuCl_4^- and
TiOH_2^+, Pd^{2+} and
TiO^- respectively. Platinum, gold and palladium
nanoparticles were uniformly highly dispersed on the titanol sites not silanol
of TiO_2/silical gel under pH=2, pH=9.9 respectively. For
the photodegradation of ethylene, they show higher photothermal efficiency than
those prepared with other pH conditions under UV illumination in a
non-circulating photoreactor. The optimum weight loadings of Pt. Au, and Pd
were 0.25 wt%, 0.5 wt%, 1 wt%, respectively. The synergistic effect enhanced
ethylene removal and CO_2 production. These results verify
that the best photothermal synergistic effect depends on the dispersion, size
of noble metal nano-particles. FTIR analyses of the used Pt-, Pd-TSO catalysts
indicated that no significant by-products were accumulated on the surface of
the catalysts, leading to them longer lifetime.
