Alkaline earth metals source

Alkaline earth metals in general, and sodium in particular, are detrimental to the FCC catalyst. Sodium permanently deactivates the catalyst by neutralizing its acid sites. In the regenerator it causes the zeolite to collapse, particularly in the presence of vanadium. Sodium comes from two prime sources ... 

A borate crosslinking agent can be boric acid, borax, an alkaline earth metal borate, or an alkali metal alkaline earth metal borate. The borate source, calculated as boric oxide, must be present in an amount of 5% to 30% by weight. 

The auxiliary electrolyte is generally an alkali metal or an alkaline earth metal halide or a mixture of these. Such halides have high decomposition potentials, relatively low vapor pressures at the operating bath temperatures, good electrolytic conductivities, and high solubilities for metal salts, or in other words, for the functional component of the electrolyte that acts as the source of the metal in the electrolytic process. Between the alkali metal halides and the alkaline earth metal halides, the former are preferred because the latter are difficult to obtain in a pure anhydrous state. In situations where a metal oxide is used as the functional electrolyte, fluorides are preferable as auxiliary electrolytes because they have high solubilities for oxide compounds. The physical properties of some of the salts used as electrolytes are given in Table 6.17. 

Various techniques of thin film deposition, including CVD (also abbreviated as MOCVD, metalloorganic chemical-vapor deposition) have been under intensive development for the. r-block elements, and particularly the alkaline earth metals, since the late 1980s. - The lability of the Cp rings of 49 has also made it a useful source of the... 

The alkali metals (Group 1A) and the alkaline earth metals (Group 2A) are not found free in nature because they are so easily oxidized. Their primary sources are seawater, brines of their soluble salts and deposits of sea salt. The metals are obtained from the electrolysis of their molten salts. 

Yamamoto T, Itoh H, Mori M, Mori N, Watanabe T, Imanishi N, Takeda Y, and Yamamoto O. Chemical stability between NiO/8YSZ cermet and alkaline-earth metal substituted lanthanum chromite. J. Power Sources 1996 61 219-222. 

For the alkaline-earth metals, as noted earlier, a simple flame of almost any type can be used to excite the metals. However, to be able to determine a wide range of metals, it is common to use either an acetylene-air or acetylene-nitrous oxide flame as the source of energy to excite the atoms. The burner is long with a slot at the top and produces a long narrow flame that is situated end-on to the optics receiving the emitted light. 

Zeolites are generally prepared under hydrothermal conditions in the presence of alkali (Barrer, 1982). The alkali, the source of silicon and the source of aluminium are mixed in appropriate proportions and heated (often below 370 K). A common reactant mixture is a hydrous gel composed of an alkali (alkali or alkaline-earth metal... 

U is also found in the Soviet Union where there are sources in Karelia, near Dnepropetrovsk, the Kirghiz Soviet Republic and in Transcaucasia Whereas once U ores were processed for their Ra content, Ra has now lost its commercial importance and it is considered a contaminant. Only two U ores have been processed extensively, pitchblende and carnotite. The general procedure is to solubilize the U with an acid, convert the ion to a complex carbonate (thereby removing the Fe, A1 and Mn), ppt the Pb and Cu as the sulfide, and finally, to recover the U as the ammonium uranate and hence, as the oxide U metal can be obtained from the oxide or the halide by reduction with alkali metals or alkaline earth metals. U, being highly electropositive, cannot be deposited electrolytically from aq solns. Thermal decompn of the tetra-iodide is possible (Ref 1)... 

The sulphides of the alkali metals and of the alkaline earth metals are readily decomposed by weak acids, even by carbonic acid.3 Ily the use of these sulphides and dilute sulphuric acid it is possible to obtain hydrogen sulphide in a high degree of purity. The hydrosulphides of the alkaline earth metals arc convenient sources of hydrogen sulphide, yielding the gas on treatment with carbon dioxide or even by merely heating.4 The carbon dioxide method is applied on a technical scale in the extraction of sulphur from alkali waste (see p. 50). 

Table 2 gives thermoehemica data of alkaline-earth metal hydrides. All form orthorhombic crystals. Calcium hydride is a convenient portable source of hydrogen gas, which results from its reaction with water. 

Alkaline Earth Metals Molybdenum Energy Sources and Production... 

Compounds of the alkaline earth metals occur widely in nature, and some of them have been known since antiquity. Calcium carbonate, of which limestone is one form, has been used as a building material since the Stone Age and as a source of lime (CaO) for... 

Table 7.4 Composition and Sources of the Alkaline Earth Metals...

The Poisson statistics of radioactive decay provide the major source of error in these analyses. Where the background interference was least, the standard deviation of the measured quantity of alkaline earth element is approximately 15%. In many cases, particularly when the alkaline earth metal concentration is low and the background is high, the standard deviation can be as much as 40%. Concentrations with greater uncertainties were reported as upper limits. 

Since silicon is a positive element, covalent bonds of most silicon compounds polarize as Si+-X . However, silicon can form bonds with alkaline and alkaline earth metals to give silylmetals in which silicon compomids polarize as SD-M+. These silylmetals are the source of silyl anions and react with haloaUcanes to give the corresponding organosilanes (equation 14). 

---