Other Metal Oxides

Well-defined coaxial tubular halloysite nanotubes (HNTs)/PPy nanocomposites were synthesized for use as electrode materials for supercapacitors by the in situ chemical oxidative polymerization method based on self-assembled monolayer amine-functionalized HNTs [72]. It showed their greatest conductivity (40 S/cm) at room temperature and a weak temperature dependence of the conductivity from 298 K to 423K. A maximum discharge capacity of 522 F/g after correcting for the weight percent of the PPy phase at a current density of 5 mA/cm in a 0.50 mol/L Na SO electrolyte solution could be achieved in a half-cell setup configuration for the HNTs/PPy composites electrode. 

Liu et al. synthesized the PPy-coated Ag nanocomposites with different dispersants via interface polymerization method by using the redox reaction of silver nitrate (in water) and Py (in CCl ) [74]. The results showed that the dispersant had strong effect on the morphology of the obtained composites. A typical core-shell structure was formed because of the addition of PVA with outer thickness of 100 nm and central core of 200 nm. Electrochemical performances indicated that the SC reached 635.5 F/g of the Ag/PPy nanocomposites at a constant current of 2.45 mA/g and retained 97% of the initial value after 50 cycles. 

Patil et al. synthesized PPy/polyacrylic acid (PAA)Zsilver (Ag) composite electrodes by chemical polymerization via a simple and cost-effective dip-coating technique for supercapacitor application [75]. The higher SC and specific energy of the PPY/PAA/Ag composite of 226 F/g and 17.45 

Wh/kg were obtained, compared to those of the PPy/PAA composite of 145 F/g and 7.18 AA /kg, respectively. It was reported that the presence of Ag nanoparticles on the PPy spherical granules could provide the least 

Wei et al. directly deposited the PPy-Ag composites on nickel foam via the redox reaction between Py and silver nitrate [76]. The nickel foam was able to accelerate the redox reaction and lead to the formation of PPy-Ag composites, which shows a strong adhesive force to the substrate. The high SC of 493 F/g at a current density of 1 A/g was determined for the PPy-Ag-nickel foam electrode. It decreased to 451.08 F/g in the first 150 circles, and it kept nearly unchanged in the subsequent 850 circles. It indicated that the PPy-Ag-modified nickel foam electrode might be promising and can be applied in flexible energy-storage devices. 

1 Glatter, O. and May, R. (2006) Small-angle techniques, in International Tables for Crystallography, vol. C (eds E. Prince and T.R. Welberry), International Union of Crystallography, pp. 89-112. 

2 Glatter, O. and Kratky, O. (1982) Small-Angle X-Ray Scattering, Academic Press, London. 

3 Feigin, LA. and Svergun, D.l. (1987) Structure Analysis by Small-Angle X-Ray and Neutron Scattering, Plenum Press, New York. 

4 Craievich, A.F. (2002) Synchrotron SAXS studies of nanostructured materials and colloidal solutions a review. Mater. Res., 5, 1-11. 

5 Peterlik, H. and Fratzl, P. (2006) Small-angle X-ray scattering to characterize nanostructures in inorganic and hybrid materials chemistry. Monatsh. Chem., 137, 529-543. 

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Of little use commercially except as a route to anthraquinone. For this purpose it is oxidized with acid potassium dichromate solution, or better, by a catalytic air oxidation at 180-280 C, using vanadates or other metal oxide catalysts. 

Iron oxides react with other metal oxides to give ferrates. ... 

Ma.gnesium Oxide. Magnesium oxide behaves in a similar manner to other metal oxides. However, most spars contain practically no magnesium oxide, so it does not affect yield loss or plant operation. 

Oxidation of methanol to formaldehyde with vanadium pentoxide catalyst was first patented in 1921 (90), followed in 1933 by a patent for an iron oxide—molybdenum oxide catalyst (91), which is stiU the choice in the 1990s. Catalysts are improved by modification with small amounts of other metal oxides (92), support on inert carriers (93), and methods of preparation (94,95) and activation (96). In 1952, the first commercial plant using an iron—molybdenum oxide catalyst was put into operation (97). It is estimated that 70% of the new formaldehyde installed capacity is the metal oxide process (98). 

Alkaline Fuel Cell. The electrolyte ia the alkaline fuel cell is concentrated (85 wt %) KOH ia fuel cells that operate at high (- 250° C) temperature, or less concentrated (35—50 wt %) KOH for lower (<120° C) temperature operation. The electrolyte is retained ia a matrix of asbestos (qv) or other metal oxide, and a wide range of electrocatalysts can be used, eg, Ni, Ag, metal oxides, spiaels, and noble metals. Oxygen reduction kinetics are more rapid ia alkaline electrolytes than ia acid electrolytes, and the use of non-noble metal electrocatalysts ia AFCs is feasible. However, a significant disadvantage of AFCs is that alkaline electrolytes, ie, NaOH, KOH, do not reject CO2. Consequentiy, as of this writing, AFCs are restricted to specialized apphcations where C02-free H2 and O2 are utilized. 

Reaction with Meta/ Oxides. The reaction of hydrogen chloride with the transition-metal oxides at elevated temperatures has been studied extensively. Fe202 reacts readily at temperatures as low as 300°C to produce FeCl and water. The heavier transition-metal oxides require a higher reaction temperature, and the primary reaction product is usually the corresponding oxychlorides. Similar reactions are reported for many other metal oxides, such as Sb202, BeO, AI2O2, andTi02, which lead to the formation of relatively volatile chlorides or oxychlorides. 

Activators. Activators are chemicals that increase the rate of vulcanization by reacting first with the accelerators to form mbber soluble complexes. These complexes then react with the sulfur to achieve vulcanization. The most common activators are combinations of zinc oxide and stearic acid. Other metal oxides have been used for specific purposes, ie, lead, cadmium, etc, and other fatty acids used include lauric, oleic, and propionic acids. Soluble zinc salts of fatty acid such as zinc 2-ethyIhexanoate are also used, and these mbber-soluble activators are effective in natural mbber to produce low set, low creep compounds used in load-bearing appHcations. Weak amines and amino alcohols have also been used as activators in combination with the metal oxides. 

Na[Sb(OH)g], respectively. The latter compound is one of the least soluble sodium salts known and is useful in sodium analysis. Numerous polyantimonate(V) derivatives are prepared by heat treatment of mixtures of antimony trioxide and other metal oxides or carbonates. Of these, K Sb O [12056-59-6] and K Sb O [52015-49-3] have been characterized by x-ray. These consist of three-dimensional networks of SbO in which corners and edges are shared with K" ions located in tunnels through the network (23). Simple species such as SbO and Sb20 2, analogous to orthophosphate and pyrophosphate, apparendy do not exist. 

Approximately 5% of the U.S. consumption of is in agriculture. Boron is a necessary trace nutrient for plants and is added in small quantities to a number of fertilizers. Borates are also used in crop sprays for fast rehef of boron deficiency. Borates, when apphed at relatively high concentration, act as nonselective herbicides. Small quantities of borates are used in the manufacture of alloys and refractories (qv). Molten borates readily dissolve other metal oxides usage as a flux in metallurgy is an important apphcation. Other important small volume apphcations for borates are in fire retardants for both plastics and ceUulosic materials, in hydrocarbon fuels for fungus control, and in automotive antifreeze for corrosion control (see Corrosion and corrosion inhibitors). Borates are used as neutron absorbers in nuclear reactors. Several borates, which are registered with the Environmental Protection Agency (EPA) can be used for insecticidal purposes, eg, TIM-BOR. 

SiHca, alumina, and other metal oxides and salts have been used as the stationary phase in gas—soHd chromatographic systems. The appHcabiHty of these materials is limited by the difficulty of producing a consistent, resiHent, reproducible material. 

At a much earlier stage in the research and development cycle, fluidized-bed processes use porous sorbents containing copper oxide (82), cerium oxide (83), and other metal oxides (84). 

Ethjl Silicate-Bonded Investments. These investments are mixtures of powder and Uquid. The powder consists of refractory particles of sUica glass, crystobahte, and other metal oxides plus magnesium oxide. The Uquid is a hydrated sUica, tetrasUicic acid [10193-36-9] Si [OH], that is suppUed in a stabUized form it can be developed by mixing ethyl sUicate [78-10 ] denatured ethyl alcohol [64-17-5] and hydrochloric acid [7647-01 -OJ. The binding of the powder is accompUshed by the formation of a sUica gel according to the reaction ... 

Hydrofluoric acid, at relatively high concentrations and at elevated temperatures, dissolves columbite-tantalite concentrates at a reasonable rate. The dissolution process is based on the fluorination of tantalum, niobium and other metal oxides and their conversion into soluble complex fluoride acids yielding complex fluoride ions. 

At above the critical pressure of 3,203.6 psi, virtually no solids can be tolerated in boiler FW because all of the water is converted to steam, which passes through the turbine. Copper corrosion products tend to be the most troublesome contaminant in supercritical boilers, consequently all efforts must be made to prevent copper and other metallic oxides from entering the boiler. FW quality guidelines include ... 

By using a similar procedure for the preparation of hybrids of silica, hybrids materials consisting of other metal oxides were also prepared by the group of Wilkes [15]. For example, titania was incorporated into organic polymers by using the chemically controlled condensation (CCC) method for the preparation of poly(tetramethylene oxide)-silica or poly(dimethylsiloxane)-silica hybrids. Especially, in the case of the hybrid with poly (tetramethylene oxide), the modulus or ultimate strength of the hybrid increased in the presence of titania component, as shown in Table 3. This phenomenon was explained by the catalytic ability of... 

There is virtually no knowledge of the setting and stmcture of copper phosphate cements. Mostly, they are complex materials. The simplest was based on a powder containing 91-5% CuO and 8-4% CO3O4. Others contained respectively 62-2 % CuO and 29-8 % ZnO, and 23-9 % Cu O and 66 7% ZnO, with other metal oxides. The strength of these cements is about the same as the zinc phosphate cement (Ware, 1971). There are also pseudo-copper cements, which are zinc phosphate cements coloured by minor amounts of copper(II) oxide. 

The chlorination of titanium dioxide (titania) is thus entirely feasible at 900 °C. Similarly, many other metal oxides can be converted to metal chlorides by reaction with chlorine in the presence of carbon. It should be noted that carbon itself is not easily chlorinated as the standard free energy of formation of carbon tetrachloride is positive at temperatures above 500 °C. 

Thermal treatment—Processes in which vapor-phase contaminants are destroyed via high-temperature oxidation the primary categories of thermal treatment used to treat MTBE and other oxygenates include thermal oxidation, which employs a flame to generate the high temperatures needed to oxidize contaminants, and catalytic oxidation, which employs lower temperatures in the presence of a catalyst (typically platinum, palladium, or other metal oxides) to destroy contaminants. 

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],... 

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