Catalysts lanthanide oxides

Catalyst systems containing lanthanides lanthanide oxides as the majority component. 

In the case of silver-modified manganese systems, recent studies agree that the addition of silver increases the activity of methane oxidation, both in the case of Ag-Mn composite catalysts and Ag modified Mn02 catalysts (35,36). Silver-manganese-lanthanide oxide catalyst systems also were shown to be highly active, and recent studies suggested the reasons for this high activity (37). 

It is concluded that copper-oxide catalyst system, particularly copper-lanthanide oxide catalyst system, show a high activity for CO hydrogenation. The effective condition of the catalyst is the homogeneous mixture of copper and oxide where a fine particle of the oxide dispersed homogeneously in the copper metal and the active eatalyst can be prepared from the mixed oxide of CueOgLnfNOj) and the homogeneous oxide mixture obtained from the calcination of the hydroxide coprecipitate. If the combined oxides were changed. 

Lanthanide Oxides. Otsuka and his colleagues at the Tokyo Institute of Technology studied the catalysts for methane oxidative coupling extensively. Twenty-five metal oxides were... 

Idemitsu Kosan Co. report that the addition of alkali halides to basic oxides (such as alkaline earth oxides or lanthanide oxides) resulted in methane oxidation catalysts that produced good yields of ethylene. A LiCl/EUjOj catalyst at 750 C gave a methane conversion of 37% with an ethylene selectivity of 46% and an ethane selectivity of 4.5%. 

Oxidation catalyst. The oxidation of alcohols to aldehydes or ketones by iodo-sylbenzene is catalyzed by this salt. Other lanthanide(III) nitrates are also effective, but LnCl. are inferior. 

The best catalyst for the synthesis of methanol from CO + H2 mixtures is copper/zinc oxide/alumina. Intermetallic compounds of rare earth and copper can be used as precursors for low-temperature methanol synthesis as first reported by Wallace et al. (1982) for RCu2 compounds (R = La, Ce, Pr, Ho and Th). The catalytic reaction was performed under 50 bar of CO + H2 at 300°C, and XRD analyses revealed the decomposition of the intermetallic into lanthanide oxide, 20-30 nm copper particles and copper oxide. Owen et al. (1987) compared the catalytic activity of RCux compounds, where R stands mainly for cerium in various amounts, but La, Pr, Nd, Gd, Dy and even Ti and Zr were also studied (table 4). The intermetallic compounds were inactive and activation involved oxidation of the alloys using the synthesis gas itself. It started at low pressures (a few bars) and low temperatures (from 353 K upwards). Methane was first produced, then methanol was formed and it is believed that the activation on, for example, CeCu2, involved the following reaction, as already proposed for ThCu2 (Baglin et al. 1981) ... 

Yasuda et al. [35] proposed the use of lanthanide oxychlorides as efficient solid catalysts for PC synthesis from supercritical CO and PO without additional organic solvent. Lanthanide oxides generally act as basic catalysts while lanthanide chlorides exhibit Lewis acidity. Thus, the latter provides the synergistic combination of the activation of CO by the Lewis basic sites and the activation of PO by the Lewis acidic (Ln ) sites. 

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