Aluminosilicate-based materials

Wuest et al. have also prepared a related tetrahedral tecton 8.63, which also produces a diamondoid polymeric framework. In this case, the solid-state network is seven-fold interpenetrated, with one diamondoid lattice filling much of the large cavities in those adjacent. It is possible that the interpenetration in this instance is a result of the self-complementary nature of the host, which contains an equal number of hydrogen bond donor and acceptor sites. However, even in this case small cavities exist, which are filled by two molecules of butyric acid per host formula unit. The formation of these kinds of framework materials opens entirely new possibilities for tailor-made porous materials with very large cavities, although it is unlikely that purely organic frameworks will ever rival aluminosilicate-based materials for sheer mechanical strength. 

The increasingly indispensable role of atomistic and quantum mechanical simulations in inorganic crystallography is perhaps no more strikingly illustrated than in the field of silicates and zeolitic materials. The two classes of material with which we shall be concerned in this chapter, namely microporous zeolites (including both aluminosilicate-based materials and their sister compounds, the aluminophosphates (ALPOs)), and the dense silicate materials and related oxides which constitute the bulk of the Earth s mantle, have in common the fact that their structural properties may be difficult to determine by conventional experimental means. Yet highly detailed and accurate structural information is critical in understanding the properties of both these important types of material. 

Guth J-L and Kessler H 1999 Synthesis of aluminosilicate zeolites and related silica-based materials Catalysis and Zeolites, Fundamentals and Applications ed J Weitkamp and L Puppe (Berlin Springer) pp 1-52... 

Z.G. Yang, K.S. Weil, K.D. Meinhardt, J.W. Stevenson, D.M. Paxton, G.-G. Xia, and D.-S. Kim, Chemical compatibility of barium-calcium-aluminosilicate base sealing glasses with heat resistant alloys, in Joining of Advanced and Speciality Materials... 

A second area that will be important in the future is the continued development of MOFs and ZlFs [152]. Much as the discovery of AlP04-based materials revolutionized the catalyhc use of zeolites when only aluminosilicates were known, MOFs and ZlFs have the potential to revolutionize low temperature processes such as oxidations and organic reachons [153]. Newly discovered materials along these same lines are covalent organic frameworks, the so-called COFs [154]. These materials have similar channels to those known for MOFs and ZlFs but tend to have higher thermal stability. 

Glas-ionomer cements are acid-based materials (using, e.g., polyacrylic acid), whose setting reaction involves neutralization of the acid groups by powdered solid bases (calcium fluoro-aluminosilicate glasses). Resin-modified glass ionomer cements are hybrid materials prepared by the incorporation of polymerizable components such as 2-hydroxyethyl methacrylate. ... 

Barrer and Mainwaring (20) report the use of metakaolin as the aluminosilicate raw material for reaction with the hydroxides of K and Ba as well as the binary base systems Ba-K and Ba-TMA to form zeolites. Zeolite phases previously synthesized in the analogous hydrous aluminosilicate gel systems were crystallized with KOH, including phillipsite-, chabazite-, K-F-, and L-type structures. The barium system yielded two unidentified zeolite phases (Ba-T and Ba-N) and a species Ba-G,L with a structural resemblance to Linde zeolite L. Ba-G,L was reported previously by Barrer and Marshall (21) as Ba-G. Similar phases were formed in the Ba-K system and in the TMA-Ba system where, in addition, erionite-type phases were formed. The L-type structures are said to represent aluminous analogs of the zeolite L previously reported (22). 

Siliceous MCM-41, aluminosilicate MCM-41, and mesitylene based materials have also been reported by Beck et al.18 N-Brand sodium silicate solutions were added to acidic soiutions with the subsequent addition of surfactant and generation of a gel. Siliceous MCM-41 materials resulted by mixing these gels with water and heating the mixture to temperatures of 100°C for 6 days. Similar materials with different elemental compositions were prepared by using Ci2H25(CH3)3NOH/Ci surfactant solutions with sodium aluminate solutions. Ultrasil silica. 

Polyoxometalates and their derivatives can be amalgamated with a variety of ligands. An impressive array of vanadium-oxide-phosphate based materials with new electronic and structural properties has been prepared by combining the tetrahedral PO4 ligand with oxovanadate moieties. Some of these materials have open-framework containing very large cavities and channels similar to those observed in conventional aluminosilicate-based zeolites . 

For the aluminosilicate matrices, the main constituent is alumina, which is held together by a silica binder. The silica may be present as a highly porous filler between the alumina particles, as seen in the GE-based materials, or it may be a continuous Si02 film on the alumina particles, as seen in the COI-based materials (examples shown in the TEM images of Figure 5). The porosity in the former case is much finer than the porosity seen in the COI material. 

Shu, H.T. Li, D. Scala, A.A., and Ma, Y.H., Adsorption of small organic pollutants from aqueous streams by aluminosilicate-based microporous materials, Sep. Purif Technol.. 11(1), 27-36 (1997). 

Sodium alumiaate is widely used in the preparation of alumina-based catalysts. Aluminosilicate [1327-36-2] can be prepared by impregnating siHca gel with alumiaa obtained from sodium alumiaate and aluminum sulfate (41,42). Reaction of sodium alumiaate with siHca or siHcates has produced porous crystalline alumiaosiHcates which are useful as adsorbents and catalyst support materials, ie, molecular sieves (qv) (43,44). 

The polyelectrolyte cements are modern materials that have adhesive properties and are formed by the cement-forming reaction between a poly(alkenoic acid), typically poly(acrylic acid), PAA, in concentrated aqueous solution, and a cation-releasing base. The base may be a metal oxide, in particular zinc oxide, a silicate mineral or an aluminosilicate glass. The presence of a polyacid in these cements gives them the valuable property of adhesion. The structures of some poly(alkenoic acid)s are shown in Figure 5.1. 

Materials formed by acid-base reactions between calcium aluminate compounds and phosphate-containing solutions yield high-strength, low-permeability, C02-resistant cements when cured in hydrothermal environments. The addition of hollow aluminosilicate microspheres to the uncured matrix constituents yields slurries with densities as low as approximately 1200 kg/m, which cure to produce materials with properties meeting the criteria for well cementing. These formulations also exhibit low rates of carbona-tion. The cementing formulations are pumpable at temperatures up to 150° C. 

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