Alkali aluminates metals

The structure analysis of nitrites, however, shows that they contain isolated NO " groups in complexes of trivalent metals, e.g. in the alkali aluminates (KA102) that have the same bruto composition as the nitrites, the coordination, indeed, is higher. Here the AI3 ions are surrounded by six oxygen ions, a coordination number that is as to be expected for a really ionic compound. Hypochlorites ACIO, chlorites AC102, chlorates AG103, sulphites A2S03, etc., all have coordination numbers that are smaller than those to be expected in ionic compounds. 

M en freshly precipitate, it is insoluble in H,0 soluble in acids and solutions of the fixed alkalies. When dried at a temperature above 50° (122° F ), or after 24 hours contact with the mother liquor, its solubility is greatly diminished. With acids it forms salts of aluminium and with alkalies, aluminates of the alkaline metal. Heated to near redness it is decomposed into A1,0, and H O. A soluble modification is obtained by dialysing a solution of ALH O in A1,C1 or by heating a dilute solution of aluminium acetate for 0 houra... 

The alkali metal hydroxides are also readily absorb CO2 and H2S to form carbonates (or hydrogencarbonates) and sulfides (or hydrogen-sulfides), and are extensively used to remove mercaptans from petroleum products. Amphoteric oxides such as those of Al, Zn, Sn and Pb react with MOH to form aluminates, zincates, stannates and plumbates, and even SiC>2 (and silicate glasses) are attacked. 

Alkali metall-trialkyl-hydrido-aluminate reagieren dagegen hauptsachlich unter Mono-hydroaluminierung zu Alken-(l)-yl-aluminiumhydriden12 (weiteres s. ds. Handb., Bd. XIII/4, S. 159ff.). 

Aluminas, which were prepared from sodium aluminate and which retained about 0.1 % of sodium ions, had a large amount of weakly acid sites, and were therefore excellent dehydration catalysts. At the same time these aluminas did not isomerize cyclohexene, owing to the absence of strong acid sites, which were neutralized by the alkali metal ions. Pines and Haag (36) determined that the upper limit of the total number of acid sites, capable of dehydrating butanol, and of the number of strong acid sites, capable of isomerization of cyclohexene, was 10 X 10 and 8 X 10 sites per cm, respectively. 

Reacts with calcium and magnesium hydrides in tetrahydrofuran forming tetrahydro aluminates, Ca(AlH4)2 reacts with hydrides of alkali metals in ether forming aluminum hydride ... 

Tanaka et al. reported that gasoline POX over Rh, Pt, and Pt-Rh is promoted by alkali (Li) and alkaline earth metals (Ba, Ca, K) supported on magnesium aluminate spinel. The catalysts were tested isothermally at 800°C at an air to fuel ratio of 5.1 and GHSV 50,000 h Li, Mg and MgLi promoters were added to Pt supported on MgAl204 spinel. All catalysts produced similar H2 and CO reformate concentrations of 23 and 25 vol%, respectively. There was a discernable difference in the carbon deposition. The unpromoted Pt catalyst showed carbon levels of 0.02 wt% carbon, where the alkali and alkaline earth promoted Pt catalysts had carbon levels of 0.01 wt%. 

Metallic manganese certainly dissolves readily in 1 mol L-1 aqueous acid, as expected, but in aqueous base a coating of insoluble Mn(OH)2 would form immediately, stopping the predicted reaction. In cases such as aluminum [E° for A13+/A1(s) = -1.67 V], the product Al is soluble in alkali as the aluminate ion Al(OH)4+ but not in neutral water, in which the... 

Beryllium reacts readily with sulfuric, hydrochloric, and hydrofluoric acids. Dilute nitric acid attacks the metal slowly, whereas concentrated nitric acid has litde effect. Hot concentrated alkalies give hydrogen and the amphoteric beryllium hydroxide [13327-32-7], Be(OH)2. Unlike the aluminates, the beryllates are hydrolyzed at the boil. 

Metal Contaminants and Ash. Alkali metals form basic oxides that are very reactive toward acidic species such as the acid gases, silicates, and aluminates. These form stable salts with acid gases if the off-gas contains such gases. Sodium, the most common of these metals, prefers to form chlorides ahead of sulfates. Sodium carbonate only forms in the absence of halides and sulfur oxides, SO. There usually is too litde NO present to form... 

Aluminum is an amphoteric element that acts as a nonmetal in alkali and develops a hydrated gelatinous aluminate of a species [Al(OH)4]. As a result of this reaction, certain suspended matter including polysaccharide polyanions coprecipitates by entrainment. This element, applied in atomic or ionic form, is a common technique for commercial isolation of pectin. In acid, Al3+ supposedly neutralizes polyanions to yield the aluminum salt. After precipitation of the pectin-aluminum complex, the metal ligand is removed by acidification and washing. 

There is wide agreement that substitution of alkali metal ions retards the early reaction of the aluminate phase, which is thus less for the orthorhombic than for the cubic polymorphs (S35,B43,RI3). The effect has been attributed to structural differences, but the early reaction of pure C, A is also retarded by adding NaOH to the solution, and the OH ion concentration in the solution may be the determining factor (S35). The reaction of C,A is also retarded by iron substitution and by close admixture with ferrite phase formation of a surface layer of reaction products may be a determining factor, at least in later stages of reaction, and the retarding effect of such a layer may be greater if it contains Fe (B44). 

Solution of zinc, aluminium, and tin in concentrated caustic alkalis evolves hydrogen, with formation of the zincate, aluminate, nnd stannate of the alkali-metal ... 

The oxides and the metals also dissolve in alkali bases as well as in acids. The oxides and hydroxides of In and Tl are, by contrast, basic hydrated T1203 is precipitated from solution even at pH 1 to 2.5. The nature of the aluminate and gallate solutions has been much studied by Raman and nmr spectra. The principal species in solution for Al is [Al(OH)4] only where Na+ is the cation is there evidence for species in solution that may be related to solids that crystallize from aluminate solutions. The latter contain dimeric anions with 4-coordinate Al, [(H0)3A10A1(0H)3]2 , and others with octahedral Al3+. 

The observation that only dark gray, spongy aluminum containing alkali metal is deposited by electrolysis of 1 1 complexes of alkali metal fluorides with aluminum trialkyls made it seem useful to try to suppress alkali metal deposition by adding Eiluminum trialkyls to the 1 1 complexes [118]. It is well known that aluminum trialkyls react easily with alkali metals, for example with sodium, to give alkali metal tetraalkyl aluminates and aluminum metal [135]. 

In 1954, Lehmkuhl in his dissertation discussed two alternative mechanisms for the cathodic deposition and anodic dissolution of aluminum from the new organo-aluminum electrolytes [118]. One possibility is the preliminary deposition of alkali metals as a result of electrolytic dissociation of the 1 2 complex, resulting in alkali metal cations, and subsequent chemical reaction of this alkali metal with free or coordinated aluminum trialkyl, yielding aluminum metal and alkali metal tetraalkyl aluminate (see Scheme 2). 

Another form of alkali metal attack on the hot faces of refractory linings involves their high temperature reaction with various components of the brick to form expansive crystalline phases which cause brick to bloat on their hot faces and, subsequently, erode or spall. An example Is the case of alumina brick exposed to sodium at temperatures from about 1700°F to 3000°F. Although sodium does not form a low temperature melt with alumina, it reacts with the alpha phase of alumina, corundum, to form beta alumina, sodium aluminate. Beta alumina has a much greater volume than the very dense corundum and, therefore, disrupts the brick bonding matrix, causing eventual bond failure. 

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