Calcination aluminosilicates

The calcined aluminosilicate, SA, is known to have on its surface a large number of protonic sites. However, the surface protons cannot be... 

Chem. Descrip. Calcined aluminosilicate CAS 1327-36-2 EINECS/ELINCS 215-475-1 Uses Extender, reinforcing agent for interior/exterior architectural coatings... 

Anortal [Anorthosite aluminium] A process for extracting alumina from anorthosite ore (a calcium aluminosilicate) by leaching with hydrochloric acid, precipitating aluminum trichloride hexahydrate, and calcining this. Developed and piloted by I/S Anortal in Norway in the late 1970s but not commercialized. 

Blanc A process for extracting alumina from leucite ore (a potassium aluminosilicate) in which the ore is leached with hydrochloric acid, aluminum trichloride is crystallized, and this is calcined to alumina. Invented by G.A. Blanc in 1921 and used in Italy from 1925 to 1943. 

All the silica present in the bauxite was converted to insoluble sodium aluminosilicate, which represented a loss of sodium and aluminum. The aluminum hydroxide was calcined to the oxide, and the sodium carbonate solution was concentrated for re-use. The process was developed by H. E. St-Claire Deville in the 1860s the carbon dioxide stage had been invented earlier by H. L. Le Chatelier. It was superseded by the Bayer process. 

Microcalorimetry experiments with NH3 and pyridine as probe molecules indicated that insertion of Ga into the offretite aluminosilicate structure increased the overall acid sites strength of the crystals while decreasing its acid sites density [255], The observed heterogeneity of acid site strength distribution of H,Ga,Al-offretites was attributed to some extra-framework Al(Vl) and Ga(Vl) species generated during the ion exchange and calcination procedures used to prepare H-offretite crystals. 

Ultramarine is essentially a three-dimensional aluminosilicate lattice with entrapped sodium ions and ionic sulfur groups (Fig. 32). The lattice has the sodalite structure, with a cubic unit cell dimension of ca. 0.9 nm. In synthetic ultramarine derived from china clay by calcination (see Section 3.5.3), the lattice distribution of silicon and aluminum ions is disordered. This contrasts with the ordered array in natural ultramarines. 

Two synthesis variables seemed to have received most attention in the work reviewed here, the cation composition and the nature and source of the aluminosilicate reactant. Extensive use of mixed bases of the alkali, alkaline earth, and organic cations have been reported as well as a wide variety of reactant aluminosilicates including solutions, hydrogels, glasses, kaolin (raw and calcined), and naturally occurring zeolites. 

Figure 4 shows the27 A1 NMR spectrum of a calcined sample. There are three peaks visible, a peak due to octahedrally coordinated aluminum (Oh), a peak due to tetrahedrally coordinated aluminum (Td) and a peak in between due to highly distorted tetrahedral sites. The tetrahedrally coordinated aluminum can be assumed to be incorporated into the aluminosilicate network while the octahedrally coordinated aluminum is occluded in the pores or exists as an amorphous by product. 

Fig 1A shows the XRD pattern of the calcined MCM-41 sample synthesized from C,6TMAB-silica and aluminosilicate systems with the Si/Al = oo(sample I) and 37(sample II) by using the delayed neutralization process. In both materials, there exist at least 4 sharp XRD peaks, which indicate well-ordered hexagonal structure of MCM-41. It means that the incorporation of aluminum into silica framework could not have significant effect on the arrangement of MCM-41 mesostructure. When the nitrogen adsorption-desorption isotherms... 

Thermal stability has been studied under various conditions calcination by heating the sample in air to 1073 K for 4 h. These samples are denoted C. The vapor-treated samples, designated by the letter V, were prepared as following the purely siliceous SBA and aluminosilicates AlSBA were placed in a fix-bed reactor. Oxygen flow saturated with water... 

Vanadyl naphthenate (in benzene) was used to metal load aluminas and aluminosilicate gels according to an established procedure (15) the naphthenate was obtained from Pfaltz and Bauer, Inc., and contained 2.9 wt% V. Decomposition of the naphthenate was performed by calcining the impregnated materials for 10 hours at 540 C in air. All catalysts were then steam-aged for five hours with -100% steam at 760 C in a fluidized bed. 

Analysis of vanadium-loaded model materials (such as EuY, amorphous aluminosilicate gels and EuY-gel mixtures) by electron paramagnetic resonance (EPR) has provided information concerning metal oxidation state and stereochemistry (67). EPR data has indicated that when vanadyl cations are introduced in the form of vanadyl naphthenate, they were stabilized in a zeolite with the faujasite structure as pseudo-octahedral V02+ even after calcination at 540°C. Upon steaming, these V02+ cations were then converted almost entirely to V+5 species (67). The formation of EuV04 was verified but the concentration of this vanadate was never proportional to the total rare-earth content of the zeolite. In EuY-gel mixtures the gel preferentially sorbed vanadium where it was stabilized mainly in the form of V205. 

In their original synthesis of MCM-41, Beck et al. (1992) achieved the hydrothermal conversion of aluminosilicate gels in the presence of quaternary ammonium surfactants (e.g. hexadecyltrimethylammonium ions). The washed and air-dried products were calcined at 450°C to remove residual organic material. 

Components of fluidized cracking catalysts (FCC), such as an aluminosilicate gel and a rare-earth (RE) exchanged zeolite Y, have been contaminated with vanadyl naphthenate and the V thus deposited passivated with organotin complexes. Luminescence, electron paramagnetic resonance (EPR) and Mossbauer spectroscopy have been used to monitor V-support interactions. Luminescence results have indicated that the naphthenate decomposes during calcination in air with generation of (V 0)+i ions. After steam-aging, V Og and REVO- formation occurred. In the presence of Sn, Tormation Of vanadium-tin oxide species enhance the zeolite stability in the presence of V-contaminants. 

While aluminum occurs most conunonly in aluminosilicate minerals, its extraction from them is prohibitively difficult. It is therefore prepared from bauxite in a two-step procedure. First, bauxite is purified by the Bayer process this involves dissolution in aqueous NaOH, separation from insoluble impurities (red mud containing Fc203), and then precipitation of A1(0H)3 by treatment of the solution with carbon dioxide. Calcining at 1200 °C produces AI2O3, which is subsequently electrolyzed to produce aluminum metal. The electrolysis is... 

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