Copper-manganese oxide

The high activity that supported gold catalysts have shown for CO oxidation at ambient temperature makes them ideal candidates for use as respiratory protectors. A copper manganese oxide, Hopcalite, has been used for many years to remove CO in toxic environments. Thus, supported gold catalysts may be chosen in the future. 

Hutchings, G.J., Copperthwaite, R.G., Gottschalk, F.M., Hunter, R., Mellor, J., Orchard, S.W., and Sangiorgio, T. A comparative evaluation of cobalt chromium oxide, cobalt manganese oxide, and copper manganese oxide as catalysts for the water-gas shift reaction. Journal of Catalysis, 1992, 137, 408. 

He et al. [20] investigated the influence of La doping on the WGS activity of Cu-Mn catalysts. 0.5% doped catalyst shows better activity. They proposed that the doped La greatly enhanced the synergistic effect of copper-manganese oxide catalysts. 

Low Temperature Oxidatix)n. The majority of heterogeneous catalysts used for oxidation are used at elevated temperatures. However, some of these metal oxide systems are capable of catalyzing specific oxidation reactions at ambient temperature. The most widely studied catalyst of this type is the mixed oxide CuMn204, which is active for the oxidation of carbon monoxide at room temperature. The same catalyst is also an active oxidation catalyst at increased temperatures, and this has been demonstrated in the previous section. The mixed copper manganese oxide is called hopcalite and was first discovered around 90 years ago (96). Early studies demonstrated that manganese oxides promoted with various transition metal oxides were active catalysts. 

X. Li, J. Xu, L. Zhou, F. Wang, J. Gao, C. Chen, et al.. Liquid-phase oxidation of toluene hy molecular oxygen over copper manganese oxides, Catal. Lett. 110 (2006) 255—260. 

Q. Tang, X. Gong, P. Zhao, Y. Chen, Y. Yang, Copper—manganese oxide catalysts supported on alumina physicochemical features and catal3dic performances in the aerobic oxidation of benzyl alcohol, Appl. Catal. A General 389 (2010) 101—107. 

Li et al reported that the activity of a copper-manganese oxide supported catalyst... 

Wollner, A., Lange, F., Schmelz, H., et al. (1993). Characterization of mixed copper-manganese oxides supported on titania catalysts for selective oxidation of ammonia, Appl. Catal. A Gen., 94,181-203. 

Li, X., Xu, J., Zhou, L., et al (2006). Liquid-Phase Oxidation of Toluene by Molecular Oxygen over Copper Manganese Oxides, Catal Lett., 110, pp. 149-154. 

G. J. Hutchings, A. A. Mirzaei, R. W. Joyner, M. R. H. Siddiqui, and S. H. Taylor, Ambient temperature CO oxidation using copper manganese oxide catalysts prepared by coprecipitation effect of ageing on catalyst performance, Catalysis Letters, vol. 42, no. 1-2, pp. 21-24, 1996. 

A. A. Mirzaei, H. R. Shaterian, M. Habibi, G. J. Hutchings, and S. H. Taylor, Characterisation of copper-manganese oxide catalysts effect of precipitate ageing upon the structure and morphology of precursors and catalysts, Applied Catalysis A, vol. 253, no. 2, pp. 499-508, 2003. 

Tellurite, see Tellurium dioxide Tenorite, see Copper(II) oxide Tephroite, see Manganese silicate(l—)... 

Metals. Transition-metal ions, such as iron, copper, manganese, and cobalt, when present even in small amounts, cataly2e mbber oxidative reactions by affecting the breakdown of peroxides in such a way as to accelerate further attack by oxygen (36). Natural mbber vulcani2ates are especially affected. Therefore, these metals and their salts, such as oleates and stearates, soluble in mbber should be avoided. 

Most commercial sorbic acid is produced by a modification of this route. Catalysts composed of metals (2inc, cadmium, nickel, copper, manganese, and cobalt), metal oxides, or carboxylate salts of bivalent transition metals (2inc isovalerate) produce a condensation adduct with ketene and crotonaldehyde (22—24), which has been identified as (5). 

The thermistor material is usually a metal oxide, eg, manganese oxide. Dopants, eg, nickel oxide or copper oxide, may be added to obtain a variety of resistance and slope characteristics. The material is usually skitered kito a disk or bead with kitegral or attached connecting wkes. Figure 4 shows a typical series of steps ki the production of a disk thermistor. 

Cobalt is the thirtieth most abundant element on earth and comprises approximately 0.0025% of the earth s cmst (3). It occurs in mineral form as arsenides, sulfides, and oxides trace amounts are also found in other minerals of nickel and iron as substitute ions (4). Cobalt minerals are commonly associated with ores of nickel, iron, silver, bismuth, copper, manganese, antimony, and 2iac. Table 1 Hsts the principal cobalt minerals and some corresponding properties. A complete listing of cobalt minerals is given ia Reference 4. 

In Moroccan deposits, cobalt occurs with nickel in the forms of smaltite, skuttemdite, and safflorite. In Canadian deposits, cobalt occurs with silver and bismuth. Smaltite, cobaltite, erythrite, safflorite, linnaeite, and skuttemdite have been identified as occurring in these deposits. AustraUan deposits are associated with nickel, copper, manganese, silver, bismuth, chromium, and tungsten. In these reserves, cobalt occurs as sulfides, arsenides, and oxides. 

HydrometaHurgical processes for copper can be categorized as (/) acid extraction of copper from oxide ore (2) oxidation and solution of sulfides in waste rock from mining, concentrator tailings, or in situ ore bodies (J) dissolution of copper in concentrates to avoid conventional smelting and (4) extraction of copper from deep-sea manganese nodules. 

NE is unstable in light and air, especially at neutral and alkaline pH. Oxidation to noradrenochrome occurs in the presence of oxygen and such divalent metal ions as copper, manganese, and nickel. 

Impurities in mineral fillers can have serious effects. Coarse particles (grit) will lead to points of weakness in soft polymers which will therefore fail under stresses below that which might be expected. Traces of copper, manganese and iron can affect the oxidative stability whilst lead may react with sulphur-containing additives or sulphurous fumes in the atmosphere to give a discoloured product. 

The raw materials needed to supply about ten million new automobiles a year do not impose a difficult problem except in the case of the noble metals. Present technology indicates that each car may need up to ten pounds of pellets, two pounds of monoliths, or two pounds of metal alloys. The refractory oxide support materials are usually a mixture of silica, alumina, magnesia, lithium oxide, and zirconium oxide. Fifty thousand tons of such materials a year do not raise serious problems (47). The base metal oxides requirement per car may be 0.1 to 1 lb per car, or up to five thousand tons a year. The current U.S. annual consumption of copper, manganese, and chromium is above a million tons per year, and the consumption of nickel and tungsten above a hundred thousand tons per year. The only important metals used at the low rate of five thousand tons per year are cobalt, vanadium, and the rare earths. 

Modification of the burning rates, pressure exponents, and temp coefficients of burning rate of the fluorocarbon composites has been accomplished with copper, lead, tin, sodium, ammonium and potassium fluoborates sodium, potassium, lithium, lead, copper and calcium fluorides potassium and ammonium dichromate lead and zinc stearate cesium carbonate potassium and ammonium sulfate copper chromite oxides of magnesium, copper and manganese boron zinc dust and carbon black (Ref 75)... 

The rate of peroxide decomposition and the resultant rate of oxidation are markedly increased by the presence of ions of metals such as iron, copper, manganese, and cobalt [13]. This catalytic decomposition is based on a redox mechanism, as in Figure 15.2. Consequently, it is important to control and limit the amounts of metal impurities in raw rubber. The influence of antioxidants against these rubber poisons depends at least partially on a complex formation (chelation) of the damaging ion. In favor of this theory is the fact that simple chelating agents that have no aging-protective activity, like ethylene diamine tetracetic acid (EDTA), act as copper protectors. 

The enthalpy of absorption of 1- and 2-nitropropane on breathing mask cartridges made with carbon is such that the decomposition of the nitrated derivative can cause its ignition. This accident is aggravated when the cartridge also contains metal oxides such as copper (II) oxide or manganese dioxide. 

Manganese oxide Sulfides (copper, molybdenum, lead) Electronic conductor Electronic conductor... 

Other metal oxide catalysts studied for the SCR-NH3 reaction include iron, copper, chromium and manganese oxides supported on various oxides, introduced into zeolite cavities or added to pillared-type clays. Copper catalysts and copper-nickel catalysts, in particular, show some advantages when NO—N02 mixtures are present in the feed and S02 is absent [31b], such as in the case of nitric acid plant tail emissions. The mechanism of NO reduction over copper- and manganese-based catalysts is different from that over vanadia—titania based catalysts. Scheme 1.1 reports the proposed mechanism of SCR-NH3 over Cu-alumina catalysts [31b],... 

Gasgnier M (2000) Ultrasound effects on metallic (Fe and Cr) iron sesquioxide (a-, y-Fe203) calcite copper, lead and manganese oxides as powders. Ultrason Sonochem 7 25-39... 

Mixtures with mercury (II) oxide and manganese dioxide prepared at — 80°C ignited at 20° and reacted violently at 15°C, respectively. Copper(II) oxide reacted vigorously at 25 °C without ignition. 

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