Aluminum sources

The X-radiation from magnesium and aluminum sources is quite complex. The principal Ka lines are, in fact, unresolved doublets and should correctly be labeled Kai 2-Besides the Kai 2 lines a series of further lines, so-called satellite lines, also exist of which the most important ones are Ka3 4. The energy separations of the satellite lines for Mg and A1 together with their intensities, related to Kaj 2, are given in Tab. 2.3. 

In zeolite synthesis (ref. 2) an aqueous mixture containing a silicon source, an aluminum source, an alkali source (usually NaOH) is autoclaved and subjected to hydrothermal treatment. Hydrated Na-ions are then filling the pore system in the as-synthesized zeolite. In the case of relatively high Si/Al zeolites an organic template is required which is usually a tetraalkylammonium compound, applied as the bromide or the hydroxide. 

The flexibility of the synthesis method provides for opportunities to incorporate other elements besides silicon. One of the first elements added was Al (11). Soon after the discovery of the silicon based TUD-1, it was found that adding suitable aluminum sources to the above procedure yielded very similar Al-Si-TUD-1 stractures. Since then, many other TUD-1 variants have been prepared. Most TUD-1 variants are either Si-TUD-1 or an M-Si version, where M is another element (e.g.,... 

Mesoporous silica was prepared using sodium silicate as silica source and cetyltrimethylammoniumbromide (CTMABr) as template as elsewhere [7]. The aluminosilicates were prepared with a similar procedure by using sodium aluminate as aluminum source, which was dissolved in the surfactant solution as described before [3]. Si/Al molar ratios were of 6, 10, 30 and 80, the impregnated iron amount was 6 wt. 

Typically, for production of zeolites (Figure 4.8), a silicon source such as sodium silicate and an aluminum source such as sodium aluminate, are prepared in solutions containing sodium and water contents as required for the formation of the respective zeolite [6], These solutions are mixed in a reactor and reacted at temperatures typically in the range between 80 and 200°C. The reaction time may vary from hours to days, and for reactions at temperatures > 100°C the reactions have to... 

Previous experiments consisted of aluminum rods as an aluminum source. This approach was revealed to be unacceptable due to the aluminum oxide forming barriers to liquid diffusion. A single slug of aluminum was substituted for the rods to reduce the effect of the aluminum oxide. 

The influence of the nature of the aluminum source on the acidic properties of mesostructured materials (MCM41) has also been studied in the literature [244]. Microcalorimetry experiments using ammonia as a probe molecule have shown that Al insertion into the mesoporous silicate framework affected acid site strength and distribution in a manner controlled by the synthesis conditions (materials prepared... 

Figure 1-a shows the 27A1 MAS NMR spectrum of the AISBA sample. It exhibits three lines at 52 ppm, about 35 ppm and 0 ppm, corresponding to four-, penta- and hexa- coordinated aluminum species. This proves that a part of the aluminum source is incorporated in the framework of this sample, though there is still some non-framework aluminum. These non-framework aluminum can be eliminated by washing the solid in NH4CI solution (Figure 1-b). 

For most of the biochemical and physiological studies involving the putative A1F4 anion, the fluoride source is usually sodium fluoride and the aluminum source is aluminum nitrate or aluminum chloride. Solutions are usually prepared with millimolar concentrations of sodium fluoride and micromolar concentrations of the aluminum source. 

The synthesis of Al-MCM-41 has been reported by several authors and the distribution between framework and extra-framework aluminum species has been found to depend strongly on the silica and aluminum sources, the nature of templating surfactant and synthesis conditions [Ref 2 and references therein]. In this contribution we investigate a simple preparation method based on hexadecyltrimethylammonium cloride, tetraethyl orthosilicate, aluminum isopropoxide and an ammonia solution. 

For the electrolytic deposition of aluminum there are various types of aprotic organic electrolytes which can be distinguished by their aluminum source ... 

It is informative to consider the dynamics that ultimately lead to an Al-N trimer rather than an Al-N tetramer. In both cases above the aluminum source was the same, trimethylaluminuin. Thus, it is reasonable to examine the amine. The more sterically demanding amine, H2NCgH3Pr 2, with the isopropyl groups give the trimer while the amine with less steric constraints around the... 

Crystalline AIN with low carbon incorporation (0.3%) can also be made from the imide-amide oligomer starting with H3Al-NMe3 as the aluminum source and an overpressure of NH3 In a similar manner, pyrolysis of a solid having the composition [Ga(NH)3/2] is useful in preparation of GaN having low carbon incorporation... 

Reddy, K.M. and Song, C.S. Synthesis of mesoporous molecular sieves Influence of aluminum source on A1 incorporation in MCM-41. Catalysis Letters, 1996, 36, 103. 

ATPH (Scheme 2-5). Aluminum tris(2,6-di-/er/-butyI-4-methylphenoxide) (ATD) [15, 16] was first reported by Barron and co-workers. They exploited a two-step synthesis of ATD starting from LiAlH4 as an aluminum source. Apparently the structural modification of aluminum aryloxides that leads to numerous variants offers real advantages over conventional Lewis acids regarding preparation and handling. 

Basic reactants used in the synthesis of zeolites include silicon source, aluminum source, metal ions, base, mineralizer, and water. Some additives such as organic template or inorganic salts could be critical for the successful crystallization of a specific zeolite. Among them, silicon source and aluminum source are the two most important reactants. Frequently used silicon source and aluminum source reactants are listed below ... 

Clay can be used as both silicon and aluminum source with or without pre-treatment. 

The synthesis of zeolites is usually conducted in slightly basic media via the condensation of silicate and aluminate. Therefore, studies on the structure and state of commonly used aluminum sources in solution are essential for studies on the synthesis of zeolites. 

Commonly used aluminum sources in the synthesis of zeolites include sodium aluminate (NaA102, Na20 54%), pseudo-boehmite, home-made aluminum hydroxide, and aluminum isopropoxide, which is the mostly used in the synthesis of microporous aluminophosphates. The structures of the two most important aluminum sources are shown in Figure 5.11 and Figure 5.12, respectively. 

Early efforts towards these resulted only in the production of lamellar aluminophosphates. Later, mesoporous aluminophosphates were synthesized successfully by using CTAB or CTAC as template and Al( PO)3 or Al(OH)3 as aluminum source.12411... 

SSZ-24 has been produced along with various impurities when aluminum at a level of Al/Si = 0.01 was introduced into the syntheses. A variety of aluminum sources were used including aluminum sulfate, metakaolin, colloidal alumina dispersed on silica (Nalco ISJ61 2), and even other zeolites (K-L, K-A, and K-offretite). However, accompanying zeolites and other impurities could not account for the catalytic activity and selectivity found in a constraint index test, described in Example 7 of the patent reference (12). The assumption then is made that the catalysis is caused by a low alumina form of the large pore SSZ-24. 

Imogolite is a natural hydrated aluminum silicate first discovered in 1962 in the clay fraction of Japanese volcanic ash and it is found widely distributed in recent volcanic deposits. Since 1977, it is possible to synthesize it in the laboratory from dilute aqueous solutions of hydroxyaluminum cations and orthosilicic acid [25] or, by reaction of tetraethylorthosilicate with an aluminum source (aluminum chloride or aluminum sec-butoxide) [26,27], at temperatures ranging from 25 to 100 °C. 

Deoxygenation of ketones. Reductive deoxygenation of ketones can be effected with an aluminum source and a Lewis acidic aluminum reagent. In the case of diaryl ketones i-BuAICh can be used as the hydride source as well as the Lewis acid. 

The presence of carbon contamination in the deposition of Al films [185] and AlGaAs epitaxial layers [186] has been attributed to the use of AIMe3. An attempt has been made to use Al(t-Bu)3 as an alternative aluminum source [187]. Unfortunately, deposition was carried out with t-BuNH2 as the nitrogen source which also causes significant carbon incorporation. 

AG), NaAlOa or Al2(S04)3 x 18 H2O as silica or aluminum source, respectively, and tetraethylammonium bromide (TEABr) or phosphoric acid as template or promoter. The gel composition and the aging and mesostructuration-crystallization conditions are indicated in Table 1. The obtained solids were dried and the occluded surfactant molecules extracted with 50 mL of ethanol at 60 °C. Subsequently, the samples were washed with distilled water, dried overnight at 60 °C and calcined in air at 350 °C for 18 h (samples 1 and 2) or at 550 °C for 6 h (samples 3, 4 and 5). 

The synthesis procedure was the following sodium aluminate (Carlo Erba) was added in a sodium-hydroxide (Carlo Erba) solution and after the homogenization the organic compound(s) (TPABr from Fluka and EG from Carlo Erba) and the silica source (silica-gel BDH) were added. In another beaker a solution of iron complex with oxalic or ortophosphoric acid, made from iron nitrate (Carlo Erba) and the specific acid (Carlo Erba), was prepared. This solution was slowly added to the aluminum silicate hydrogel. For the synthesis of the silica form, the procedure was identical but without introduction of the aluminum source. In some experiments related to the system B an amount of 3-10 wt. % of MFI (A1 and Fe free) calcined seeds was added. 

P-17 - aI-NMR studies on Al-MCM-41 molecular sieves synthesized with different Si/AI ratios and different aluminum sources... 

In this study the hydrothermal formation of ZSM-5 zeolitic coatings on the surface of different pretreated flat aluminum sheets has been investigated. The specific feature of the reported preparation method is the fact that the aluminum sheet acts as a support as well as an aluminum source as well to achieve a good connection between the support and zeolite layer. The reaction was carried out under various synthesis conditions. The obtained products were characterized by XRD, SEM and chemical analysis. 

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