Aluminosilicated gels, preparation

In addition to conventional aikoxide-based syntheses, Williams and Interrante [177] and Pouxviel et al. [175] investigated aluminosilicate gels prepared from organometallic precursors. Williams and Interrante reacted diketonate (chel) aluminum alkoxides with trimethylacetoxysilane forming heterocondensed products according to the following scheme ... 

Table 3. Some Synthetic Zeolites Prepared from Sodium Aluminosilicate Gels...

Aluminosilicate gel samples having the same composition, Me20-Al203-Si02-H20 (Me = Na, K, Rb and Cs) were prepared by two different procedures ... 

Sodium aluminate, 2 345t, 358-359 analysis, 2 275-276 economic aspects, 2 275 health and safety factors, 2 276 manufacture, 2 274-275 neutralization, 2 424 physical and chemical properties of, 2 273-274 uses of, 2 276-277 in water treatment, 26 111 Sodium aluminosilicate gels, synthetic zeolites prepared from, 16 831t Sodium aluminosilicates, 12 578 Sodium aluminum hydride, 13 621, 623-624... 

Crystallization was followed by analyzing the solid product quantitatively by x-ray powder diffraction. Prepared mixtures of a standard sample of mordenite and the amorphous substrate of mordenite composition were used to establish a calibration curve for the quantity of mordenite based on the summation of x-ray peak intensities. For zeolites A and X, the unreacted aluminosilicate gel was used to prepare mixtures with standard samples of zeolites A and X for quantitative phase identification. 

The LRS of similarly prepared V-loaded aluminosilicate gels (AAA-aluminas) are shown in Fig. 4 band positions are listed in Table 3. These spectra are essentially featureless for V concentrations below the 1%V level, Fig.4. For loadings in the 1.0 to 3.0% V range, relatively intense bands near 517 cm"1 and 700 cm"1, together with a broad shoulder centered near 815 cm and a very weak band near 1020 cm"1 can be seen in the Raman spectra of these samples, Figs. 4B-4D. Recently, Wokaun, et. al. (25) have shown Raman spectral characteristics for SiO, supporting low V loadings which are similar to those in Fig. 4 but did not indicate whether H20 influenced their results. 

Additionally, the liquid phase produced by the hydrothermal treatment can be employed as a silica source for the preparation of aluminosilicate gels for the posterior synthesis of zeolites [24,120-122],... 

Our synthetic routes to ZK4 were modifications of those described by Kerr (21). An amorphous, basic aluminosilicate gel containing tetramethylammonlum (TMA) Ion was heated at 100°C to promote formation of ZK4 crystals. Preparation of the gel Involved the vigorous mixing at room temperature of one component acting as a source of sodium and alumina, with another component acting as a source of TMA and silica. The alumina used was sodium... 

Hardly any research has been performed on ferrierite in zeolite membrane configurations. Matsukada et al. [50,51] prepared a ferrierite-based membrane by the frequently used Vapour-phase Transport Method. By using ethylenediamine, triethylamine and steam (under hydrothermal conditions), a porous alumina support, covered with the proper aluminosilicate gel, was transformed into a alumina supported (30 pm thick) ferrierite layer. No permeation with 1,3,5-triisopropylbenzene coirld be observed, proving the layer to be defect-free. Fluxes of small gases were found in the order of 10" -10 mol.m. s. Pa and decreased in the order H2>He>CH4>N2>02>C02... 

Water-free glycerol aluminosilicate gel (10.0Na20-Al203-13.9Si20-100.0glycerol) was prepared by following the same procedure as reported elsewhere i ). 

Synthesis mixture was prepared by mixing 172.1 g of water-free glycerol aluminosilicate gel with 31.0 nucleation gel into a homogeneous mixture at room temperature. 

It can be seen that an agitated medium is markedly favourable to the TON-type zeolite, the FER-type zeolite being less sensitive to this factor. The presence of seeds increases the crystallization rate for both zeolites. FER-type zeolites containing Co2 or Mg2 could be prepared with Co2 or Mg2 - ezchanged aluminosilicate gels (20). In addition to the above-mentioned templates for TON-type zeolites, two other amines, di-n pentylamine and 1,4-diamino n-pen-tane, yield the same structure. 

In 1990, Xu et al. first reported the transformation of a dry aluminosilicate gel to crystalline MFI by contact with vapors of water and volatile amines, which was named dry gel conversion (DGC).[99] Since then, this method has been extensively studied and a large number of microporous materials with new compositions and structures were prepared. Generally, DGC can be divided into vapor-phase transport (VPT) and steam-assisted conversion (SAC) according to the volatility of the SDAs. For volatile SDAs such as ethylenediamine, a mixture of water and SDA was poured into the bottom of the autoclave and then a dry gel, which does not contain any SDAs, was placed over the liquid surface. Water and SDAs were vaporized at elevated temperature (150 200 °C), reached the dry gel, and initiated the crystallization, which was called VPT. Less volatile SDAs such as tetrapropylammonium hydroxide were usually involved in the dry gel. Only water steam is supplied during the reaction, which was called SAC. 

Only scattered reports are available on the preparation of LSX even 1n an unbound form. Simply extrapolating the standard synthesis reagents and conditions used to produce typical X zeolite will not yield a S1/A1 ratio of less than 1.2. Kuhl and Sherry have published the most comprehensive Information on LSX synthesis.(10) In a British patent, they describe a preparation wherein aluminosilicate gels In highly alkaline mixed NaVK+ are subjected to a multiday aging period at 40°C, followed by... 

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