Binary oxides preparation

Photocatalysis on I itanium-Silicon Binary Oxides Prepared by the Sol-Gel Method... 

As shown in Fig. 65, titanium-silicon binary oxides prepared by the sol-gel method exhibit a characteristic photoluminescence spectrum near 480 nm upon excitation at 280 nm. The absorption and photoluminescence spectra are attributed to the charge-transfer processes on the highly dispersed tetrahedral titanium oxide species embedded in the Si02 matrices (168, 200, 201). When the titanium content of the oxides was decreased, the intensity of the photoluminescence spectrum increased, and its peak wavelength shifted to shorter wavelengths. 

There are numerous complex (ternary and quaternary) plutonium oxides. Their properties have been reviewed (30). Plutonium oxidizes readily to Pu(VI) from binary oxides to complex oxides such as Ba PuO. The best way to oxidize Pu to Pu(VII) is to prepare complex oxides such as Li PuO from Li20 and PUO2 iu flowing oxygen (85). 

The thermodynamic and other physical properties of binary oxides (e.g. A//f, AGf, mp, etc.) show characteristic trends and variations when plotted as a function of atomic number, and the preparation of such plots using readily available compilations of data can be a revealing and rewarding exercise. 

Ir catalysts supported on binary oxides of Ti/Si and Nb/Si were prepared and essayed for the hydrogenation of a,P-unsaturated aldehydes reactions. The results of characterization revealed that monolayers of Ti/Si and Nb/Si allow a high metal distribution with a small size crystallite of Ir. The activity test indicates that the catalytic activity of these solids is dependent on the dispersion obtained and acidity of the solids. For molecules with a ring plane such as furfural and ciimamaldehyde, the adsorption mode can iirfluence the obtained products. SMSI effect (evidenced for H2 chemisorption) favors the formation of unsaturated alcohol. 

A second-order structural transformation in La uC at 233 5°C was reported (118) in a thermal expansion study. The LajCu04 product was prepared at high temperature (1100°C) by the solid-state reaction of the corresponding binary oxides. The material was found to decompose above 1200°C with the loss of oxygen. Samples of La uC, prepared at 1200°C, then maintained at 750°C in vacuum, yielded products having the general composition La2Cu04.x, or... 

The remaining studies reviewed in this section deal with binary oxides that contain titania. Shibata and Kiyoura (140) measured surface acidities by the n-butylamine titration method of the Ti02-Zr02 system as a function of composition and method of preparation. Samples were prepared by calcination of coprecipitated mixtures of titanium and zirconium hydroxides that were made by ammonia or urea addition. The products had... 

All of the hydrotaleite-derived magnesia supports were prepared by first coprecipitating magnesium aluminum hydroxycarbonate in the presence of Mg and Al nitrates, KOH, and K2C03 according to procedures already described (8,9). Hydrotaleites were then decomposed by calcination at 873 K for 12-15 h to yield the binary oxide to be used for a catalyst support. The specific surface area of the hydrotaleites determined by nitrogen adsorption was typically about 220 m2g 1 after calcination. X-ray powder diffraction patterns of the materials were recorded on a Scintag X-ray diffractometer. 

Tn our recent work on the systems Rh-O, Pt-O (5, 7), and Au—O (5,6) at high oxygen pressures, we prepared new compounds in all three systems. We conducted a similar study in the system Pd-O, but were not able to synthesize any new binary oxides of palladium. The divalent oxide, PdO, appears to be stable even at high oxygen pressures. 

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