Alumina trihydroxide

Silca, crystalline-quartz, 628 Chromyl chloride, 175 Fthylidene norbornene, 335 Methomyl, 443 Cobalt hydrocarbonyl, 182 Decaborane, 203 Benomyl, 67 Diborane, 211 Pentaborane, 555 Osmium tetroxide, 546 Cesium hydroxide, 131 Alumina trihydroxide, 38 Aluminum oxyhydroxide, 38 Vinyl toluene, 738 Nonylphenol, 541 2,4-Dinitrotoluene, 279 Trimethyl benzene, 712 Methylcyclohexanol, 465 Terphenyls, 656 Isooctyl alcohol, 409 Anisidine, 52... 

The term alumina hydrates or hydrated aluminas is used in industry and commerce to designate aluminum hydroxides. These compounds are tme hydroxides and do not contain water of hydration. Several forms are known a general classification is shown in Figure 1. The most weU-defined crystalline forms ate the trihydroxides, Al(OH) gibbsite [14762-49-3], bayerite [20257-20-9], and nordstrandite [13840-05-6], In addition, two aluminum oxide—hydroxides, AIO(OH), boelimite [1318-23-6] and diaspote [14457-84-2], have been clearly defined. The existence of several other forms of aluminum hydroxides have been claimed. However, there is controversy as to whether they ate truly new phases or stmctures having distorted lattices containing adsorbed or intedameUar water and impurities. 

Bayerite (P-Aluminum Trihydroxide). Bayerite is rarely found in nature. It has been synthesized by several methods A pure product is prepared by the Schm b method (3) in wliich amalgamated aluminum reacts with water at room temperature. Other methods include rapid precipitation from sodium alurninate solution by CO2 gassing, aging of gels produced by neutrali2ation of aluminum salts with NH OH, and rehydration of transition rlio alumina. 

Alumina - Alumina forms a variety of oxides and hydroxides whose structures have been characterized by X-ray diffraction (16). From the catalytic viewpoint y-alumina is the most important. This is a metastable phase that is produced from successive dehydration of aluminum trihydroxide (gibbsite) to aluminum oxide hydroxide (boehmite) to y-alumina, or from dehydration of boehmite formed hydrothermally. y-alumina is converted into a-alumina (corundum) at temperatures around 1000 C. 

Assessment of the toxicity of aluminas has been complicated by the chemical and physical variants of the compounds and inconsistencies in the nomenclature used to describe them. The group of compounds referred to as aluminas is composed of various structural forms of aluminum oxide, trihydroxide, and oxyhydrox-ide. As these aluminas are heated, dehydration occurs, producing a variety of transitional forms temperatures between 200 and 500°C result in low-temperature-range transitional... 

Alumina is a porous, high-surface-area form of aluminum oxide. The surface has more polar characteristics than silica gel does therefore, it has both acidic and basic characteristics, reflecting the nature of the metal. Alumina has a high melting point, slightly over 2000°C, which is also a desirable property for a support due to its thermal stability. Alumina is composed of aluminum trihydroxides, Al(OH)3 aluminum oxyhydroxides, AIO(OH) and aluminum oxide, Al203n(H20). 

The commercial alumina and silica gel sorbents are mesoporous, i.e., with pores mostly larger than 20 A (see Fig. 1). Activated alumina is produced by thermal dehydration or activation of aluminum trihydroxide, A1 (OH)3 (Yang, 1997), and is crystalline. Commercially, silica is prepared by mixing a sodium silicate solution with a mineral acid such as sulfuric or hydrochloric acid. The reaction produces a concentrated dispersion of finely divided particles of hydrated Si02, known as silica hydrosol or silicic acid ... 

Boehmite is itself decomposed at c. 400—450°C. As expected, the calcined products have much lower specific surface areas than the activated aluminas produced from the trihydroxides. However, the results of de Boer and his co-workers (de Boer, 1972) indicate that a sample prepared at 580°C was highly microporous and that up to this temperature there was only a small change in the external area. 

SYNS AF 260 ALCOA 331 ALUMIGEL ALUMINA HYDRATE ALUMINA HYDRATED ALUMINA TRIHYDRATE a-ALUMINA TRIHYDRATE ALUMINIC ACID ALUMINLLM HYDRATE ALUMINUM(III) HYDROXIDE ALUMINUM HYDROXIDE GEL ALUMINUM OXIDE HYDRATE ALUMINUM OXIDE TRIHYDRATE ALUMINUM TRIHYDRAT ALUMINUM TRIHYDROXIDE ... 

Names aluminum trihydroxide, aluminum hydroxide, hydrated alumina... 

At least seven different crystaUine phases of alumina hydrates are known (Table 3.1) (4—6). Among them are four polymorphs of the trihydroxide A1(0H)3 and two polymorphs of the oxyhydroxide AlOOH. The four trihydroxides are bayerite (7,8), usually denoted as a-Al(OH)3, gibbsite (8,9), usually denoted as Y-Al(OH)3, and the less common doyleite (10,11), and nordstrandite (12). Their structures are closely related. While characterization of bayerite and gibbsite has been the subject of many investigations, details on the structure of nordstrandite and doyleite are scarce. The availability of refined theoretical methods and computational power and the combination of the respective results with diffraction and vibrational spectroscopic data recently led to reanalysis of the structure of all of these... 

CAS 21645-51-2 EINECS/ELINCS 244-492-7 Synonyms Alumina hydrate Alumina hydrated Alumina trihydrate Alumlnic acid Aluminum hydrate Aluminum oxide hydrate Aluminum trihydrate Aluminum trihydroxide ATH Hydrated alumina Hydrated aluminum oxide Trihydrated alumina Classification Inorganic compd. 

Aluminum oxide hydrate Aluminum trihydrate Aluminum trihydroxide ATH Hydrated alumina... 

Zinc-containing linseed oil-based poly(ester amide) resins with different loadings of zinc acetate were prepared by an in situ condensation polymerisation reaction between linseed oil fatty amide diol, phthaUc anhydride and zinc acetate (a divalent metal salt with different mole ratios) in the absence of any solvent (Fig. 5.3). Similarly, linseed oil based-poly(ester amide urethane)s with alumina, Zn and Cd were prepared in situ by the reaction of linseed oil-derived fatty amide diol, aluminium trihydroxide, divalent zinc/cadmium acetate and toluene-2,4/2,6-diisocyanate, using a minimal amount of solvent.Castor oil and soybean oil-based poly(ester amide) containing Cd and Zn were also prepared to obtain improved performance, including antimicrobial properties. ... 

Metal hydroxides provide an important alternative to halogenated flame retardants. Aluminium trihydroxide, sometimes known as alumina trihydrate, is the most widely used of all FRs in plastics. Magnesium hydroxide is also finding increasing acceptance, and calcium hydroxide is being marketed as an additive for different reasons. 

Aluminium trihydroxide decomposes on heating at about 190 °C to form alumina and water, according to the eqnation ... 

Table 10.3. Alumina hydrates (aluminum trihydroxides and oxihydroxides)...

In the course of mechanochemical activation the brutto composition of trihydroxide remains Al(OH)3. However, IR data point to the changes in the state of structural "water". Some OH-groups interact with one another to produce the molecular water which is shown by 7 1 NMR data to stay in the first coordination sphere of Al(III) ion /7,8,9/. As a result, the first endothermal effect on the heating curves shifts to the low-temperature region by 120° and a new exothermal effect appears at 1083 K. A sample is calcined until the effect appears. Such calcination controlled by DTA and the X-ray phase analysis indicate an X-ray amorphous alumina in the range of calcination temperatures 523-IOOOK. The exothermal effect at 1083 K is due to the transition of X-ray amorphous oxide (71-AI2O8) to T1-AI2O8. 

Metal hydroxides, in particular aluminium trihydroxide (ATH), which is a low-cost filler, and magnesium dihydroxide (MDH). The endothermic decomposition of Al(OH)3 occurs between 180 and 200°C and leads to the release of water and the formation of an insulating ceramic layer of alumina (AI2O3). The use of ATH also reduces the HRR peak aud the smoke production. Mg(OH)2 acts in a similar way but its endothermic degradation occurs at a higher temperature (over 300°C) and a protective layer of MgO is formed at the composite surface. 

The crystalline phase transformation of alumina is shown in Figure 6.14. Transformation is also dependent on the gaseous atmosphere, as well as the other conditions, as detailed in Figure 6.14. In this figure, gibbsite and bayerite are trihydroxide, Al(OH)3, or AI2O3.3H2O. Boehmite and diaspore are AlOOH. 

Aluminium trihydroxide is often incorrectly called alumina trihydrate, but fortunately the abbreviation ATH serves for both. It is also known as Gibbsite or Nordstrandite or Hydrargilhte. Some 40-50 million tpa are manufactured from bauxite ores by extraction using sodium... 

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