Aluminum metal activation

Chemical Raw Material. In addition to use as a catalyst raw material, clays are used or have been extensively studied as chemical raw material. For example, kaolin has been investigated as a raw material for aluminum metal production. Kaolin has a 38 to 40% alumina content and is available in the United States in large quantities whereas the higher alumina bauxite reserves are very limited. The Bureau of Mines has actively carried out research in the aluminum from ka olin area for many years. Activity increases whenever imports of bauxite are threatened by war or other trade intermptions (1,22,23). 

In 1970, Monroe and Rooker(28) claimed the use of aluminum salts of acid orthophosphate esters as viscosity builders for use in fracturing fluids. The application of these materials began a new era of hydrocarbon gelling agents. Monroe(29) later claimed the use of Fe30it as a metal activator of phosphate esters and in 1971 described several other metals(30) that could be used with amine neutralization agents. Numerous metallic ionic derivatives can be used as effective "activators" or crosslinkers to prepare a gel. 

Aluminum occurs naturally in soil, water, and air. It is redistributed or moved by natural and human activities. High levels in the environment can be caused by the mining and processing of its ores and by the production of aluminum metal, alloys, and compounds. Small amounts of aluminum are released into the environment from coal-fired power plants and incinerators. Virtually all food, water, and air contain some aluminum, which nature is well adapted to handle. 

Processes which involve oxidation (the loss of electrons or the gain of relative positive charge) and reduction (the gain of electrons or the loss of relative positive charge) are typical of these reactions. Use of Table 8.1, the activity series of common metals, enables chemists to predict which oxidation-reduction reactions are possible. A more active metal, one higher in the table, is able to displace a less active metal, one listed lower in the table, from its aqueous salt. Thus aluminum metal displaces copper metal from an aqueous... 

In thermites using aluminum metal as the fuel, the passivation of the metal surface with oxide must be taken into account. For micrometer sized particles of aluminum, the oxide passivation layer is negligible, but on the nano-scale this passivation layer of alumina begins to account for a significant mass portion of the nanoparticles. In addition, the precise nature of the oxide layer is not the same for all manufacturers of aluminum nanoparticles, so the researcher must use TEM to measure oxide thickness to allow calculation of active aluminum content before stoichiometric calculations are carried out for the mixing of thermites. Table 13.3 shows details of some of the percentages of aluminum in aluminum nanoparticles and shows just how significant and inconsistent the oxide layer can be. 

Solid-state hydroxyisobutylaluminoxane co-catalysts prepared by Wu [4] were as effective in activating metallocenes in olefin polymerization as the corresponding alkyl aluminoxanes but at a lower aluminum/metal ratio. 

Hydrogen. Aluminum is a very active metal. Al (aq) cannot be reduced to aluminum metal (e° = -1.66 V) the water is much more easily reduced to hydrogen (e° = 0.828 V). (See Table 17.2) (Aluminum oxide melts at too... 

Electrolysis is often used to reduce the most active metals. In Chapter 11 we considered the electrolytic production of aluminum metal. The alkali metals are also produced by electrolysis, usually of their molten halide salts. 

Therefore, the reaction will not take place. The skeleton equation for this situation is Br(l) + MgCl2(aq) NR. No balancing is required. Magnesium is listed above aluminum in the metals activity series. Therefore, the third reaction will take place because magnesium is more reactive than aluminum. In this case, magnesium will replace aluminum. The skeleton equation for this reaction is... 

Both the oxidant carbonyl compound (acetone) and the substrate alcohol are bound to the metal ion (aluminum). The alcohol is bound as the alkoxide, whereas the acetone is coordinated to the aluminum which activates it for the hydride transfer from the alkoxide. The hydride transfer occurs via a six-membered chairlike transition state. The alkoxide product may leave the coordination sphere of the aluminum via alcoholysis, but if the product alkoxide has a strong affinity to the metal, it results in a slow ligand exchange, so a catalytic process is not possible. That is why often stoichiometric amounts of aluminum alkoxide is used in these oxidations. 

Severdenko and his co-workers studied the effect of ultrasound on the dissolution rate and chemical activity of aluminum metal [124], Al disks were subjected to a 20-kHz ultrasound field and then samples were cut from sites corresponding to the potential antinode or supersonic bias antinode of the wave. The electrochemical properties and the dissolution rate of the Al samples pretreated in ultrasound fields were compared with data for blank Al samples. Their results showed that samples cut from sites located in the potential antinode of the wave were more negative than the values inherent to untreated samples. This was due to the decrease of the thermodynamic stability of the metal as a result of the formation of microdefects, microcracks, etc. The dissolution rate of the ultrasound-treated samples cut from these sites in aqueous NaOH solutions was also enhanced. The reverse effect was observed with samples cut from supersonic bias antinode sites, i.e. electrode potentials shifted in the positive direction, dissolution rate in NaOH solutions decreased, and the overall increase of the thermodynamic stability of the metal was attributed by the authors to the redistribution under the effect of the ultrasound field of dislocations to energetically more stable configurations. 

The mechanical properties of the metals, the coating, and their interaction also play a role in the process in metal activation. Two mechanisms, shown in Scheme 1, were proposed according to the hardness of the metal.Soft metals, such as alkali metals (hardness <0.6 Mohs ), undergo permanent plastic deformation to form powders. For harder metals (<2.7 Mohs, e.g., magnesium and aluminum), only superficial layers were deformed. Nevertheless, if... 

The reductive dimerization of nitroarenes is very dependent on the substitution in aromatic ring and electron-withdrawing groups (p-OCOMe, p-C02Me, and P-NO2) suppress the reaction (Table 6.17). Reaction was tested with several other metals (tin, manganese, copper, aluminum, antimony, and lead), and metal activity correlates with oxidation-reduction potentials of these metals in the order A1 > Mn > Sn > Pb > H > Sb > Bi > Cu (Table 6.18). The pathway for the deoxygenative dimerization of nitroarenes on the activated bismuth surface proceeds via the stepwise reduction processes from nitroarene to nitrosoarene and W-arylhydroxylamine, followed by dehydrative coupling. 

Using the activity series (Table 4.5), write balanced chemical equations for the following reactions. If no reaction occurs, simply write NR. (a) Iron metal is added to a solution of cop-per(II) nitrate (b) zinc metal is added to a solution of magnesium sulfate (c) hydrobromic acid is added to tin metal (d) hydrogen gas is bubbled through an aqueous solution of nickelfll) chloride (e) aluminum metal is added to a solution of cohalt(n) sulfate. 

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