Aluminates, stability

Water molecules attack high-alumina zeolites by a acid hydrolysis of the Al-O-Si bonds. The framework is decomposed inside the bulk of the crystals. High-silica zeolites are dissolved by an alkaline mechanism starting at the crystal surface. Non-framework aluminium directly formed during the dealumination or generated subsequently by a surface alumination stabilizes high-silica zeolites. Mathematical models allow the prediction of the long-term stability of molecular sieves on the basis of experimental data. 

The kinetic parameters for aldose and ketose transformations in the D-glucose-D-mannose-D-fructose system at 27 C on aluminate resin and hydroxide resin have been obtained. On both resins hydroxide ion catalyses isomerization. By complexation, resin-bound aluminate stabilizes D-fructose so that the equilibrium mixture contains 72% of the ketose. Lower temperatures were found to give the highest yields of D-fructose. A similar study on maltose gave a yield of 63% maltulose at 24 C, but higher temperatures caused elimination of D-glucose at C-4. In a study of isomerization, enolization, etc. of mono-... 

The majority of metals and alloys available depend for their resistance to corrosion on the properties of an oxide film or corrosion product which is formed initially by the corrosion process. In many cases the protectiveness of the oxide film is determined by its stability in aqueous solutions in a specific pH range, either chemically dissolving to form aquocations at lower pH values or complex anions (aluminate, ferroate, plumbate, zincate, etc.) at higher pH values (Fig. 2.22). An important property of the chemical is therefore the pH value that it develops when dissolved in water. For many materials and many chemicals this is the overriding factor and in many cases... 

Liquid junction potential 63, 549 Literature of analytical chemistry 6, 122, 156, 251, 253, 498, 499, 640, 641, 813, 815 Lithium, D. of as aluminate, (g) 459 Litmus 265 Litre xxix, 78 Littrow mounting 661 Logarithms four figure, 843 Lovibond comparator 655 Low voltage d.c. arc 763, 771 Lubricants for glass stopcocks 85 Lyophilic colloids 419 Lyophobic colloids 419 stability of, 419... 

Pipes, Table of Military High Explosives , Second Revision, NAVORD 87-46 (July 1946) 16) W.R. Tomlinson, Jr L.H. Eriksen, Stability Tests of Aluminized Explosives , PATR 1635 (21 Oct 1946) 17) A.N. Campbell ... 

Stabilization and Testing of Explosives. Aluminized Explosives , NDRC Div 8 ERL Interim Report (August 15—September 15, 1944)... 

Though of lower stability than the analogous aluminate, its reactivity is generally similar to that of the latter. 

Treatment of lead(n) chloride with aluminum trichloride and o-xylene furnishes bis(o-xylene)lead(ll) bis(tetrachloro-aluminate) 41. According to the results of an X-ray structure determination, 41 consists of a monomeric complex with two arene ligands in a distorted 77-mode of coordination and two bidentate AICI4- ions at the central Pbz+ ion. The interaction of the lead center with the tetrachloroaluminate ligands is presumably highly ionic, suggesting that 41 is a triad of arene-stabilized ions, rather than a molecule.7... 

An analysis of the thermodynamic stability models of various nickel minerals and solution species indicates that nickel ferrite is the solid species that will most likely precipitate in soils (Sadiq and Enfield 1984a). Experiments on 21 mineral soils supported its formation in soil suspensions following nickel adsorption (Sadiq and Enfield 1984b). The formation of nickel aluminate, phosphate, or silicate was not significant. Ni and Ni(OHX are major components of the soil solution in alkaline soils. In acid soils, the predominant solution species will probably be NE, NiS04°, and NiHP04° (Sadiq and Enfield 1984a). 

Stabilizing the Support Oxide. Promoter elements can be added to the support oxide resulting in a decreased Co compound formation with the support oxide. This is illustrated in Figure 3A. More specifically, strategies should be followed to avoid the formation of either cobalt titanate, cobalt silicate or cobalt aluminate as a result of Co solid-state diffusion under reducing or regeneration conditions in the subsurface of these support oxides. Some transition metals, for example Zr or La, could act in such a way. 

We will consider only two parageneses or facies of the system relevant to sepiolite-palygorskite minerals that where these minerals are stable and that just above their stability (Figure 42). This is estimated provisionally to be somewhat below 80°C. This temperature is justified through comparison with the observed stability (rv/100°C) of natural aluminous, alkali-bearing montmorillonite, which accompanies sepiolite-... 

---