Alumina Oxides

The compounds of greatest importance are aluminum oxide, the sulfate, and the soluble sulfate with potassium (alum). The oxide, alumina, occurs naturally as ruby, sapphire, corundum, and emery, and is used in glassmaking and refractories. Synthetic ruby and sapphire are used in lasers for producing coherent light. 

A detailed study of the physical and chemical adsorption of water on three xerogels, ferric oxide, alumina and titania, as well as on silica (cf. p. 272) has been carried out by Morimoto and his co-workers. Each sample was outgassed at 600°C for 4 hours, the water isotherm determined at or near 20°C, and a repeat isotherm measured after an outgassing at 30 C. The procedure was repeated on the same sample after it had been evacuated at a... 

ALUMDIUMCOMPOUNDS - ALUL IUM OXIDE (ALUMINA) - ACTIVATED] (Vol2)... 

See Adsorption, LIQUID separation Aluminum compounds, aluminum oxide (alumina) Carbon, activated carbon Ion exchange Molecular sieves Silicon... 

Traditional adsorbents such as sihca [7631 -86-9] Si02 activated alumina [1318-23-6] AI2O2 and activated carbon [7440-44-0], C, exhibit large surface areas and micropore volumes. The surface chemical properties of these adsorbents make them potentially useful for separations by molecular class. However, the micropore size distribution is fairly broad for these materials (45). This characteristic makes them unsuitable for use in separations in which steric hindrance can potentially be exploited (see Aluminum compounds, aluminum oxide (ALUMINA) Silicon compounds, synthetic inorganic silicates). 

Aluminum halides and aluminumnitrate, Aluminum oxide(Alumina),... 

The choice of selected raw materials is very wide, but they must provide calcium oxide (lime), iron oxide [1309-37-1/, siHca, and aluminum oxide (alumina). Examples of the calcereous (calcium oxide) sources are calcium carbonate minerals (aragonite [14791-73-2] calcite [13397-26-7] limestone [1317-65-3] or mad), seasheUs, or shale. Examples of argillaceous (siHca and alumina) sources are clays, fly ash, mad, shale, and sand. The iron oxide commonly comes from iron ore, clays, or mill scale. Some raw matedals supply more than one ingredient, and the mixture of raw matedals is a function of their chemical composition, as deterrnined by cost and availabiHty. 

In some parts of the world, as in Russia, fermented alcohol can serve as a cheap source for hutadiene. The reaction occurs in the vapor phase under normal or reduced pressures over a zinc oxide/alumina or magnesia catalyst promoted with chromium or cohalt. Acetaldehyde has been suggested as an intermediate two moles of acetaldehyde condense and form crotonaldehyde, which reacts with ethyl alcohol to give butadiene and acetaldehyde. 

Aluminum Oxide (Alumina, oAlumina, Corundum, Alandum). A1203, mw 101.96, v hard white cryst powd, mp 2045°, bp 2980°, d 3.965g/cc. Insol in w, v si sol in aq alkaline solns. Found in nature as a mineral such as bauxite. Lab prepn is by heating aluminum hydroxide to above 1100°. 

C.19 Aluminum oxide, alumina, exists in a variety of crystal structures, some of which are beautiful and rare. Write the formula for aluminum oxide, which is a binary compound of aluminum and oxygen. The mass of a rectangular slab of aluminum oxide of dimensions 2.5 cm X 3.0 cm X 4.0 cm is 102 g. What is the density of aluminum oxide ... 

GP 1] [R 1] A comparison of four micro reactors (see Table 3.1) with different Pt loadings (Pt impregnated on an anodically oxidized alumina support) confirmed that higher conversions were obtained at higher Pt loadings (6 vol.-% NH3, 88 vol.-% O2, balance He 600-4430 cm min (STP) 260-380 °C) [28,98]. At near complete conversion, 48% N2O selectivity was found (Figure 3.27). 

Of particular concern was the finding of a suitable catalyst Owing to the scouting nature, virtually no know-how base was available that time. The investigation gave highly valuable hints for later catalyst development. Actually, they motivated a search for catalysts of higher porosity and better defined composition. As a result, anodically oxidized alumina supports for catalysts were developed (see Sections 3.1 and 3.4.2). 

Electrolytic aluminum production is the most important process in both volume and significance. World production is about 15 megatons per year, consuming about 240 billion kilowatthours of electrical energy. Aluminum oxide (alumina), AI2O3, is subjected to electrolysis at a temperature of 950°C to this end it is dissolved in molten cryolite NujAlFg, with which it forms a eutectic melting at about 940°C. Carbon anodes that are anodically oxidized to CO2 in the process are employed. The overall electrolysis reaction can be written as... 

By using thermosensitive poly-acrylamides, it is possible to prepare cubic Pt nanocrystals (with predominant (1 0 0) facets) and tetrahedral Pt nanocrystals (rich in (111) facets). These Pt nanocrystals can be supported on oxide (alumina) and used as a catalyst in structure-sensitive reaction, NO reduction by CH4. The results proved that morphologically controlled metal nanoparticles supported on adequate support give us a novel tool to connect the worlds of surface science with that of real catalysis. 

For environmental reasons, reaction (Eqn. 21) (NO -> N2) should be promoted, N20 having a dramatic greenhouse gas effect. The different steps of reaction (Eqn. 23) have been investigated in detail, mainly by FTIR spectroscopy [61-63], One of the possible intermediate is isocyanate. NCO species could be formed on the metal and migrate on the support, which may explain the large differences observed when Rh is supported on different oxides (alumina, silica, zirconia, ceria-alumina, etc.). However, the main step should be the dissociative adsorption of NO ... 

Formation of aluminum oxide (alumina) upon contact of aluminum metal with pure water occurs because the reaction... 

B. Better tools available, but no consensus on mechanism or active site—1980 to 2006. Rhodes et al.291 published a comprehensive review on the heterogeneously catalyzed water-gas shift mechanism in 1995. Included in that discussion was the copper/zinc oxide/alumina system. The conclusion was that this system appears to be constructed of small metallic islands of copper resting on a zinc oxide alumina phase. Zinc oxide may exert some impact on catalytic activity, but it was suggested in the review that the contribution is small. It was indicated that strong evidence exists to support either a formate or a redox mechanism, and the authors even suggest the possibility that both mechanisms might occur, though insufficient data exist to determine which mechanism predominates. 

Alumina, 2 345t 5 582. See also Activated alumina Aluminum oxide (alumina) Bauxite(s) Calcined alumina Fused alumina Tabular alumina in the activated catalyst layer, 10 41 adsorption capacity vs. years of service, 1 630... 

Nickel-oxide alumina, catalytic aerogels, l 763t... 

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