Sodium /?//?"— alumina

Dehydrogenation of dipentene (d,l-limonene) and 4-vinylcyclohexene has been studied using both the lithium-ethylenediamine catalyst system (4) and the sodium-alumina catalyst system (12). The aromatic compounds p-cymene and ethylbenzene are produced by both types of catalyst however, while vinylcyclohexene yields ethylbenzene rapidly at 0° over a sodium on alumina catalyst, dipentene yields mainly mixed dienes at 0 but at 25 is also rapidly dehydrogenated to p-cymene (12). 

Amongst other new systems under study are the sodium/sulphur battery with sodium / -alumina solid electrolyte operating at 300-375°C and Li-FeS batteries operating at about 450°C. Long-term battery research is directed towards batteries that can operate at room temperature with aqueous electrolyte, such as zinc-halogen, aluminium-air, and iron-air. 

A relatively new class of luntiuescent materials are the /3"-aluminas. Sodium alumina when doped with approximately... 

Compounds in the P/P" family permit not only fast Na ion diffusion but also rapid transport of other monovalent ions (e.g., K, Ag, Cu", Cs, Rb ), hydronium ions (HsO ), divalent ions (e.g., Ca ", Ba " ) and trivalent cations . As it turns out, the Na ion has the highest mobility in these two structures. The sodium -alumina and /)"-alumina compounds are nonstoichiometric aluminates that are derivatives of the yet unknown stoichiometric sodium aluminate, NaAlnOi (Na20 IIAI2O3), with an excess of Na20. 

A relatively new class of luminescent materials are the fi"-aluminas. Sodium alumina when doped with approximately 10 Cu+ cm has a visible emission in the green, which can be tuned from the blue to the red by the addition of codopants such as Ca+, Ba+, or Ag+. ... 

Fine pores in refractories cannot be barriers for the vapors of sodium compounds. Yet the glassy-appearing sodium alumina silicate phase in the pore of 3-4 pm may close the pore, making a dead end for the subsequent penetration of sodium compounds inside the refractory. It is more problematic to create such a barrier in pores of 25 pm (Fig. 4.4). 

In the sodium—sulphur battery, patented by Ford, for example, instead of solid electrodes separated by a liquid electrolyte (as in the conventional lead—acid car battery, for example), sodium alumina is used as a solid electrolyte, specifically conducting sodium ions between liquid electrodes of sodium metal and sulphur (Figure 29.1). 

The procedure for producing thallium / -alumina from sodium / -alumina is the same as that used above for silver j -alumina. Thallium (I) nitrate is used in place of silver nitrate. For crystals of 1-mm in diameter the time to reach 99% equilibrium is about 75 h. The exchanged crystals contain less than 0.1% sodium. 

Surface heterogeneity may be inferred from emission studies such as those studies by de Schrijver and co-workers on P and on R adsorbed on clay minerals [197,198]. In the case of adsorbed pyrene and its derivatives, there is considerable evidence for surface mobility (on clays, metal oxides, sulfides), as from the work of Thomas [199], de Mayo and co-workers [200], Singer [201] and Stahlberg et al. [202]. There has also been evidence for ground-state bimolecular association of adsorbed pyrene [66,203]. The sensitivity of pyrene to the polarity of its environment allows its use as a probe of surface polarity [204,205]. Pyrene or ofter emitters may be used as probes to study the structure of an adsorbate film, as in the case of Triton X-100 on silica [206], sodium dodecyl sulfate at the alumina surface [207] and hexadecyltrimethylammonium chloride adsorbed onto silver electrodes from water and dimethylformamide [208]. In all cases progressive structural changes were concluded to occur with increasing surfactant adsorption. 

Xu Z H, Ducker W and Israelachvili J N 1996 Forces between crystalline alumina (sapphire) surfaces in aqueous sodium dodecyl sulfate surfactant solutions Langmuir 12 2263-70... 

Boron trioxide is not particularly soluble in water but it slowly dissolves to form both dioxo(HB02)(meta) and trioxo(H3B03) (ortho) boric acids. It is a dimorphous oxide and exists as either a glassy or a crystalline solid. Boron trioxide is an acidic oxide and combines with metal oxides and hydroxides to form borates, some of which have characteristic colours—a fact utilised in analysis as the "borax bead test , cf alumina p. 150. Boric acid. H3BO3. properly called trioxoboric acid, may be prepared by adding excess hydrochloric or sulphuric acid to a hot saturated solution of borax, sodium heptaoxotetraborate, Na2B407, when the only moderately soluble boric acid separates as white flaky crystals on cooling. Boric acid is a very weak monobasic acid it is, in fact, a Lewis acid since its acidity is due to an initial acceptance of a lone pair of electrons from water rather than direct proton donation as in the case of Lowry-Bronsted acids, i.e. 

The method of obtaining aluminum metal by the electrolysis of alumina dissolved in cryolite was discovered in 1886 by Hall in the U.S. and at about the same time by Heroult in France. Cryolite, a natural ore found in Greenland, is no longer widely used in commercial production, but has been replaced by an artificial mixture of sodium, aluminum, and calcium fluorides. 

To separate the oil added an equal volume of fresh cool water (note waited until solution cooled before adding the water). The oil started to drop out perfectly, used DCM to extract all traces of the oil. This woik up is by far the cleanest, easiest and simplest to date... (This dreamer was tried all method of ketone synthesis)... Once the oil was extracted, the extracts were pooled washed with sodium bicarbonate lx, saturated solution of NaCI 1x, and two washes with fresh dHzO... Some time was required for the work up as there was a little emulsion from the use of the base wash and then with the first water wash. The JOC ref suggested using an alumina column to remove the catalyst (could be a better way to go). 

Aqueous solutions of caustic soda aie highly alkaline. Hence caustic soda is ptimatily used in neutralization reactions to form sodium salts (79). Sodium hydroxide reacts with amphotoric metals (Al, Zn, Sn) and their oxides to form complex anions such as AlO, ZnO. SnO ", and (or H2O with oxides). Reaction of AI2O2 with NaOH is the primary step during the extraction of alumina from bauxite (see Aluminum compounds) ... 

Starch is a polysaccharide found in many plant species. Com and potatoes are two common sources of industrial starch. The composition of starch varies somewhat in terms of the amount of branching of the polymer chains (11). Its principal use as a flocculant is in the Bayer process for extracting aluminum from bauxite ore. The digestion of bauxite in sodium hydroxide solution produces a suspension of finely divided iron minerals and siUcates, called red mud, in a highly alkaline Hquor. Starch is used to settle the red mud so that relatively pure alumina can be produced from the clarified Hquor. It has been largely replaced by acryHc acid and acrylamide-based (11,12) polymers, although a number of plants stiH add some starch in addition to synthetic polymers to reduce the level of residual suspended soHds in the Hquor. Starch [9005-25-8] can be modified with various reagents to produce semisynthetic polymers. The principal one of these is cationic starch, which is used as a retention aid in paper production as a component of a dual system (13,14) or a microparticle system (15). 

There are several processes available for the manufacture of cryoHte. The choice is mainly dictated by the cost and quaUty of the available sources of soda, alumina, and fluoriae. Starting materials iaclude sodium aluminate from Bayer s alumina process hydrogen fluoride from kiln gases or aqueous hydrofluoric acid sodium fluoride ammonium bifluoride, fluorosiUcic acid, fluoroboric acid, sodium fluosiUcate, and aluminum fluorosiUcate aluminum oxide, aluminum sulfate, aluminum chloride, alumina hydrate and sodium hydroxide, sodium carbonate, sodium chloride, and sodium aluminate. 

The manufacture of cryoHte is commonly iategrated with the production of alumina hydrate and aluminum trifluoride. The iatermediate stream of sodium aluminate from the Bayer alumina hydrate process can be used along with aqueous hydrofluoric acid, hydrogen fluoride kiln gases, or hydrogen fluoride-rich effluent from dry-process aluminum trifluoride manufacture. 

Aluminum Industry. Large amounts of HE are consumed in the production of aluminum fluoride [7784-18-17, AIE, and cryoHte [15096-52-3] (sodium aluminum fluoride), used by the aluminum industry. Both of these compounds are used in the fused alumina bath from which... 

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