Oxygen aluminum

The surface of activated alumina is a complex mixture of aluminum, oxygen, and hydroxyl ions which combine in specific ways to produce both acid and base sites. These sites are the cause of surface activity and so are important in adsorption, chromatographic, and catalytic appHcations. Models have been developed to help explain the evolution of these sites on activation (19). Other ions present on the surface can alter the surface chemistry and this approach is commonly used to manipulate properties for various appHcations. 

The vanadium alloy is purified and consoHdated by one of two procedures, as shown in the flow diagram of the entire aluminothermic reduction process presented in Figure 1. In one procedure, the brittle alloy is cmshed and heated in a vacuum at 1790°C to sublime most of the aluminum, oxygen, and other impurities. The aluminum faciHtates removal of the oxygen, which is the feature that makes this process superior to the calcium process. Further purification and consoHdation of the metal is accompHshed by electron-beam melting of pressed compacts of the vanadium sponge. 

Trivalent Oxides.—It is probable that the rhombohedral crystal corundum, AI2O3, consists of ions that is, the bonds are probably electrostatic. The oxygen ions are arranged in layers parallel to the base (111) within each layer the distances between adjacent ions are 2.50 and 2.89 A., the values being somewhat uncertain because of the difficulty in the accurate determination of the parameter. These values are probably compatible with the oxygen radius 1.40 A., calculated for crystals with bivalent cations. The aluminum-oxygen distances are 1.85 and 1.99 A., in satisfactory agreement with the calculated radius sum 1.90 A. 

The aluminum reduction of a refractory metal oxide invariably yields a metal product containing significant amounts of residual aluminum and oxygen, represented usually as a metal-aluminum-oxygen alloy. When the metal contains aluminum in addition to oxygen, a number of reactions can occur during pyrovacuum treatments. These are ... 

Aluminosilicates Minerals composed primarily of the elements aluminum, oxygen, and sfiicon. 

Combustion of aluminum particle as fuel, and oxygen, air, or steam as oxidant provides an attractive propulsion strategy. In addition to hydrocarbon fuel combustion, research is focussed on determining the particle size and distribution and other relevant parameters for effectively combusting aluminum/oxygen and aluminum/steam in a laboratory-scale atmospheric dump combustor by John Foote at Engineering Research and Consulting, Inc. (Chapter 8). A Monte-Carlo numerical scheme was utilized to estimate the radiant heat loss rates from the combustion products, based on the measured radiation intensities and combustion temperatures. These results provide some of the basic information needed for realistic aluminum combustor development for underwater propulsion. 

In an electron transfer reaction, an element undergoing oxidation loses electrons, whereas an element gaining electrons undergoes reduction. In the aluminum-oxygen example, the aluminum was oxidized, and the oxygen was reduced because every electron tranter reaction involves simultaneous oxidation and reduction. These reactions are frequently called redox reactions. 

The driving force for this reaction is the strength of the aluminum-oxygen bond relative to the aluminum-nitrogen bond. This reaction provides a good way of making synthetically useful amides of /V - in c th o x y - /V - m c th y I a in i n c.134 Trialkylamidotin and bis(hexamethyldi-... 

In the third chapter Wheatley and Linton describe new developments in the remarkable chemistry of aluminum and oxygen. While compounds featuring an aluminum-oxygen bond find widespread utility (as catalyst supports and co-catalysts, for example) there is still a great deal that is not understood in how these compounds form. This chapter provides the necessary basic information upon which further applications may be developed. 

If sea water is first deaerated, only a small amount of corrosion inhibitor, if any, probably would be needed to prevent attack on steel, or copper-base alloys. For aluminum, oxygen is needed to promote a protective film. 

Strong mineral acids react with clays to hydrolyze aluminum-oxygen bonds. The aluminum dissolves, leaving an altered structure. Protons in the acid also exchange with sodium and other alkali cations, leaving an acidic material. Houdry took advantage of such reactions in making the active acidic catalysts... 

According to Loewenstein s rule (73), two aluminum-oxygen tetrahedra could never be in neighboring positions because of the strong Coulomb repulsion. Therefore, the following four possible types of hydroxyl groups can... 

Treatment of the reaction mixture with aqueous acid cleaves the aluminum-oxygen bond and produces cyclohexanol. 

The amphoterism and facile hydrolysis of hydrates of aluminum salts make it impossible to prepare anhydrous salts by dehydration. For example, the strength of the aluminum-oxygen bond in [Al(H20)6]Cl3 precludes the formation of A1 Cl bonds and AI2O3 is obtained upon heating (equation 7). 

Aluminum isdDutoxide (AIB) or mixtures with tetraethoxysilane (TEOS) were precipitated with a stoichiometric amount of water to hydrolyze all of the aluminum-oxygen and silicon-oxygen bonds. 

Unlike uranium pentaehloride, which is thermally unstable, protactinium pentachloride sublimes unchanged above 180°C in vacuo. It is a yellow, moisture-sensitive solid which is slightly soluble in benzene, tetrahydrofuran, and carbon tetrachloride. Visible absorption speetra have been reeorded for solutions in the last two solvents and in aleohol (110). Reactions with hydrogen, aluminum, oxygen, and silicon tetra-iodide are discussed below. It is unaffected by carbon monoxide at 350°C in a sealed tube. 

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