Carbon cerium content

Abimanyu etal. studied the synthesis of DMC by ethylene carbonate transesterification with methanol (step 2) with various MgO-CeOs mixed oxide catalysts at 150°C. They showed that a high ethylene carbonate conversion of 64% (DMC selectivity of 95%) could be obtained by a catalyst with a cerium content around 25 mo %P... 

In the soil the lanthanides are immobile under a wide variety of pH conditions, due to the low solubility of salts such as carbonates and phosphates. ConcenU ations in ground water are much lower than those of the soil through which the water percolates. In most natural waters, because the lanthanides sorb strongly to silicates and humic material, the bulk of the Ln content including cerium is associated with such colloidal particulates [44]. In the marine environment a depletion of cerium relative to the other lanthanides is found that is attributed to the oxidation of cerium (III) to highly insoluble Cc(IV) (OHjj-type species. 

This study focused on the deactivation of the Mn/Ce catalysts during reaction. The catalytic oxidation of phenol in aqueous solution to carbon dioxide, water and other side-products was selected as the test reaction. Catalysts were prepared from amorphous precursors using the citrate method and controlling the calcination temperature. Activity performance as a function of the time on stream was studied by simultaneously analyzing the conversion of phenol, the total organic carbon content of the catiyst, the cations eluted and the elemental composition of both cerium and manganese. Experimental conditions were widely varied. Fresh and used catalysts were also analyzed by BET surface area, X-Ray Diffraction and X-Ray Photoelectron Spectroscopy. 

Cerium chloride has also been used to accelerate the oxidation of 10-decenal to the acid by the action of hydrogen peroxide in the presence of ammonium molybdate and potassium carbonate (Trost and Masuyama, 1984). This supports the contention that the hydrate of the alcohol is the species being oxidized (Luche and Gemal, 1979). Further study is required to establish the general utility of the method, however. 

Phase X-ray diagrams of solid solution based on cerium dioxide, obtained by synthesis via carbonates using 95% of precipitator is presented in Fig. 15.1. The research has shown that samples with fluorine mass fiaction less than 2% contain only one phase cerium oxide, except for the sample containing 0.5% fluorine. Further introduction of fluorine from 3 to 8% leads to oxyfluoride phase (LnOF) separation. There are three phases (CeO, LnOF and LnFj) when fluoride content is more than 9%. Samples with 80% of precipitator have the same phase composition. The residts of the quantitative phase and structural analysis of samples, synthesized via... 

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