Composites with Other Metal Oxides

In this section, we will focus on metal oxides with binary structures (M Oy). Moreover, composites containing other metal oxides and/or catalysts (e.g., Pt or Au) will also be considered. 

Antimony trioxide is insoluble in organic solvents and only very slightly soluble in water. The compound does form a number of hydrates of indefinite composition which are related to the hypothetical antimonic(III) acid (antimonous acid). In acidic solution antimony trioxide dissolves to form a complex series of polyantimonic(III) acids freshly precipitated antimony trioxide dissolves in strongly basic solutions with the formation of the antimonate ion [29872-00-2] Sb(OH) , as well as more complex species. Addition of suitable metal ions to these solutions permits formation of salts. Other derivatives are made by heating antimony trioxide with appropriate metal oxides or carbonates. 

The electrical conductivity also increases with increasing metal oxide content, due to the high mobility of the metal ions. For example several glass compositions have been used as solid electrolytes in galvanic cells in which other metal ions apart from the alkaline and alkaline earth ions have been incorporated. The electrochemical cell... 

Recent sol-gel methods have been recognized as promising procedures to prepare catalysts [12-14]. The sol-gel methods allows a unique way of catalyst design, because they represent an ab initio synthesis of the final solid from well defined molecular compounds [13]. By suitable choice of reagents, reaction and drying conditions, such technique allows to predefine pore structure, porosity, composition, surface polarity and crystallinity or amorphicity of metal oxides [12]. In principle, any metal that forms stable oxides can be forced to copolymerise with other metals in sol-gel procedures to provide mixed metal oxides [13]. 

From results obtained with metallic and metallic oxide catalysts they conclude, that metallic catalysts do not accelerate the oxidation of hydrogen and carbon monoxide so exclusively as do the metallic oxide catalysts. With a metal catalyst, all the gases present have to react with a temporary intermediate oxide. On the other hand, hydrogen and carbon monoxide can directly reduce the oxide catalysts even at low temperatures, while the hydrocarbons cannot. For this reason hydrogen and carbon monoxide are more readily formed with a metallic catalyst than with a metallic oxide catalyst. It is evident that they do not consider equilibrium relationships of any importance since the composition of products is explained on the basis of relative reaction rates. Although this attitude may be well taken on the basis of the results, the fact that methane is very unreactive and requires an active catalyst for oxidation at low temperatures to form intermediates does not seem to have been recognized. 

The chloride-formation reaction of nickel oxide and other metal oxides with HCl gas were studied at temperatures from 25 to 500°C and at 1.0 atm. The experiments were carried out by using gas analysis, a thermobalance and X-ray analysis to determine compositions for the reaction ... 

CNTs can be combined with various metal oxides for the degradation of some organic pollutants too. Carbon nanotubes/metal oxide (CNT/MO) composites can be prepared by various methods such as wet chemical, sol gel, physical and mechanical methods. To form nanocomposite, CNTs can be combined with various metal oxides like Ti Oj, ZnO, WO3, Fc203, and AI2O3. The produced nanocomposite can be used for the removal of various pollutants. Nanoscale Pd/Fe particles were combined with MWNTs and the resulted composite was used to remove 2,4-dichlorophenol (2,4-DCP). It was reported that the MB adsorption was pH-dependent and adsorption kinetics was best described by the pseudo-second-order model. Iron oxide/CNT composite was reported to be efficient adsorbent for remediation of chlorinated hydrocarbons. The efficiency of some other nanocomposites such as CNT/ alumina, CNT/titania and CNT/ZnO has also been reported [60-62]. 

The combinations of boron with oxidizers other than lead compounds seem to be less subject to accidental ignition than comparable mixtures of sensitive metals and oxidizers. Boron is used extensively in first fires and delay compositions and may be useful as a specialty heat source. Because of the small amount of boron required in combination with heavy metal oxides, certain mixtures can be used... 

Two steel tanks were removed from the same site and at the same time as the composite tank. There are no records to show how long these steel tanks were in service. One of the steel tanks was dusted with white metal oxide corrosion, while the other had signs of corrosion at the weld line. Rust had weakened the joint so much that the weld line could be scraped away with a pocket knife, revealing holes. Corrosive attack on an underground gasoline tank comes from both the inside and outside. An inside problem is moisture, which is often present in the fuel and settles at the bottom. Depending on various conditions, the moisture can create severe internal corrosion. But an inspection of the 25 year old composite tank showed no internal corrosion, even though there was moisture with the fuel on the bottom. 

The chromium oxide film on the surfaces prevents wetting of the base metal by the molten filler and must therefore be removed by a suitable flux. Stainless steels can easily be joined together with other metallic materials or stainless steels of other composition. All conventional brazing processes, such as furnace, torch, induction and resistance brazing, can be employed. The most commonly used process is furnace brazing. 

However, contemporarily, not much significant work has been reported dealing with the thermal stability behaviour of other metal oxide filled SR composites. Zhuang et observed that the thermogram of nano-ZnO/NR... 

To the best of our knowledge, no Pt-based catalyst is able to promote the selective oxidation of ethanol to either CO2, acetic acid or acetaldehyde. However, the product composition can be modified by alloying Pt with other metals. For example, the addition of Sn to Pt increases the catalytic activity and also the production of acetic acid, while the addition of Ru improves the electrical performance without changing the product selectivity. Several authors have demonstrated that Ru and Sn are able to activate water al lower potential than pnre Pt, thus boosting the formation of CO2 and acetic acid, while Sn is particularly suited to reduce C-C bond breaking through a sort of dilution of adjacent Pt atoms. ... 

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