Manganese-uranium oxides

Strangely enough, a combination similar to the ammonia catalyst, iron oxide plus alumina, yielded particularly good results (32). Together with Ch. Beck, the author found that other combinations such as iron oxide with chromium oxide, zinc oxide with chromium oxide, lead oxide with uranium oxide, copper oxide with zirconium oxide, manganese oxide with chromium oxide, and similar multicomponent systems were quite effective catalysts for the same reaction (33). 

Oxides.—Amongst the simple oxides may be classed —oxide of chromium, oxide of iron, oxide of uranium, oxide of manganese, oxide of zinc, oxide of cobalt, oxide of antimony, oxide of copper, oxide of tin. 

The first member of this family, manganese, exhibits One of the most interesting redox chemistries known thus it has already been discussed in detail above. Technetium exhibits the expected oxidation states, and associated with these are modest emf values. All of the isotopes of technetium are radioactive but "Tc has a relatively long half-life (2.14 k 10s years) and is found in nature in small amounts because of the radioactive decay of uranium. Oxidation slates of rhenium range from +7 to - 3, with some species ReOj and Re3+) unstable with respect to disproportionation. 

It is claimed that a catalyst mixture of 93% uranium oxide and 7% molybdenum oxide gives relatively high yields. The oxidation is sometimes carried out in the liquid phase by using manganese dioxide/sulfuric acid at 40°C. 

T1 ecent investigations have shown that chromium, manganese, cobalt, nickel, copper, and zinc oxides react with uranium oxides at elevated temperatures to form double oxides with the formulas MUO4 and MU3O10. Table I lists eight compounds for which some structural and thermal stability information has been reported. 

Formaldoxime has been applied in the determination of manganese in water [69,70], plants [69,71], silicate and carbonate minerals [72], uranium oxide [9], tin [73], and alkalies [74]. The formaldoxime method has been automated in the determination of manganese in water [75] and in silicate minerals [76]. The FIA technique has been applied in the analysis of natural waters [77] and silicates [78]. 

Procedure. Weigh out samiTLes of ore estimated to contain an amount of uranium oxide less them 100 mg. but sufficient to be detected by the chosen method of analysis. Add 20 ml. of 20 by volume sulfuric acid and 2 grams of manganese(XV) oxide. Heat the mixture to boiling. Allow to cool to room temperature. Dilute with approximately 50 ml. of water. Adjust to a pH between 1.0 and 1.5 by the dropwise addition of 20 sodium hydroxide. Filter through fine-pore filter paper using tyto 10-ml. portions of water to wash the residue on the paper. 

Catalysts used for preparing amines from alcohols iaclude cobalt promoted with tirconium, lanthanum, cerium, or uranium (52) the metals and oxides of nickel, cobalt, and/or copper (53,54,56,60,61) metal oxides of antimony, tin, and manganese on alumina support (55) copper, nickel, and a metal belonging to the platinum group 8—10 (57) copper formate (58) nickel promoted with chromium and/or iron on alumina support (53,59) and cobalt, copper, and either iron, 2iac, or zirconium (62). 

Sihca is reduced to siUcon at 1300—1400°C by hydrogen, carbon, and a variety of metallic elements. Gaseous siUcon monoxide is also formed. At pressures of >40 MPa (400 atm), in the presence of aluminum and aluminum haUdes, siUca can be converted to silane in high yields by reaction with hydrogen (15). SiUcon itself is not hydrogenated under these conditions. The formation of siUcon by reduction of siUca with carbon is important in the technical preparation of the element and its alloys and in the preparation of siUcon carbide in the electric furnace. Reduction with lithium and sodium occurs at 200—250°C, with the formation of metal oxide and siUcate. At 800—900°C, siUca is reduced by calcium, magnesium, and aluminum. Other metals reported to reduce siUca to the element include manganese, iron, niobium, uranium, lanthanum, cerium, and neodymium (16). 

Oxides and hydroxides Bauxite laterites copper oxide ores uranium ores zinc ores and calcines manganese ores and nodules... 

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