Platinum-oxide species formed on progressive oxidation of platinum crystallites supported on silica and silica-alumina
- National Tsing-Hua Univ., Hsinchu (Taiwan, Province of China)
Samples of platinum crystallites finely dispersed on silica and silica-alumina were prepared by impregnating a series of SiO{sub 2}-Al{sub 2}O{sub 3} supports with aqueous PtCl{sub 4} solutions. Reduced platinum samples were oxidized by dioxygen to examine variations of platinum-oxides (Pt-O{sub x}) species formed with the oxidation temperature (T{sub O}). Both PtO and PtO{sub 2} species were verified to coexist on oxidized Pt/SiO{sub 2} samples according to characterizations by techniques of X-ray photoelectron spectroscopy and temperature-programmed reduction (TPR). TPR spectra of oxidized platinum species dispersed on SiO{sub 2}-Al{sub 2}O{sub 3} supports exhibited six peaks of different reduction temperatures (T{sub r}). These peaks were assigned to PtO and PtO{sub 2} species dispersed in silica-rich grains (T{sub r} = {minus}40 and 20 C, respectively), in alumina-rich grains (T{sub r} = 50 and 90 C), and in pores of the grain boundary (T{sub r} = 110 and 130 C), respectively. The contribution of these six species varied with both the temperature of oxidation treatments and the Al{sub 2}O{sub 3}/SiO{sub 2} ratio of sample supports.
- OSTI ID:
- 328296
- Journal Information:
- Journal of Catalysis, Vol. 182, Issue 1; Other Information: PBD: 15 Feb 1999
- Country of Publication:
- United States
- Language:
- English
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