Aluminium borosilicate

With the aim of developing microchip CE systems from materials that have properties similar to those of glass but are easier and less expensive to fabricate, a ceramic material, aluminium borosilicate, has been employed [8]. Although electroosmotic properties are similar to those of fused silica and fabrication can be accomplished using either milling or laser ablation, its use has not been widespread. 

PVC, polythene and PTFE if moist gas is used Stainless steel, copper, nickel. Monel, brass, aluminium for dry gas <200°C. Borosilicate glass for low pressures. For moist gas, copper and polyvinylidene chloride plastics Monel and nickel Monel and nickel Most common metals so long as gas is dry... 

Elements such as B, Ga, P and Ge can substitute for Si and A1 in zeolitic frameworks. In naturally-occurring borosilicates B is usually present in trigonal coordination, but four-coordinated (tetrahedral) B is found in some minerals and in synthetic boro- and boroaluminosilicates. Boron can be incorporated into zeolitic frameworks during synthesis, provided that the concentration of aluminium species, favoured by the solid, is very low. (B,Si)-zeolites cannot be prepared from synthesis mixtures which are rich in aluminium. Protonic forms of borosilicate zeolites are less acidic than their aluminosilicate counterparts (1-4). but are active in catalyzing a variety of organic reactions, such as cracking, isomerization of xylene, dealkylation of arylbenzenes, alkylation and disproportionation of toluene and the conversion of methanol to hydrocarbons (5-11). It is now clear that the catalytic activity of borosilicates is actually due to traces of aluminium in the framework (6). However, controlled substitution of boron allows fine tuning of channel apertures and is useful for shape-selective sorption and catalysis. 

Porous materials can also be coated with zeolite films by direct synthesis. For example, microcellular SiOC ceramic foams in the form of monoliths were coated on their cell walls with thin films of silicalite-1 and ZSM-5 using a concentrated precursor solution for in situ hydrothermal growth (Fig. 9).[62] The zeolite-coated monoliths show a bimodal pore system and are thermally stable to at least 600 °C. A related strategy is based on the conversion of macroporous Vycor borosilicate glass beads, having pores of about 100 nm, to MFI-type zeolite-containing beads retaining the same macroscopic shape.[63] This conversion was achieved by hydrothermal treatment with an aluminium source and a template such as TPABr. 

The yields of aluminium and silicon are nearly constant for all the experiments, the yield of aluminium loeing slightly higher. The yield of incorporation of boron, instead, is very low when the synthesis gel is aluminium-rich (exp. -4). Boron and aluminium are incorporated at the same extent only when the available boron largely exceeds aluminium (exp. 5, 6). This behaviour can be accounted for by a competition between the Kinetics of incorporation of borosilicate and aluminosilicate units in the zeolite. No rate constants can be established without a knowledge of the partition coefficients of the elements between the liquid and solid phases of the synthesis gel. Anyway, the higher crystallization efficiency of the... 

Partial substitution of boron for aluminium in the synthesis is a suitable tool to control not only the composition, but also the crystal size of the zeolite beta The nucleation flow of the zeolite is a nonlinear function of the composition of the parent gel. The composition of the crystals, instead, depends on the relative rate of sticking of Independent borosilicate and aluminosilicate species. 

Dielectric materials used in ozone production include borosilicate glass, titanium dioxide and aluminium dioxide. Glass is the most common dielectric material in use. 

Holderich has demonstrated the advantage offered by zeolite catalyst to the chemical industry. Many previously unknown synthesis steps are possible with zeolite catalysts. Two examples of the several dozens of potential and already implemented processes reviewed by Hdiderich are the synthesis of acetylimidazole, and the formation of isoprene from 3-methylbutylaldehyde. In the latter reaction a basic zeolite catalyst has a significantly longer lifetime than an acidic one. A surprising number of acid catalysed reactions use the extremely weakly acidic borosilicate analogs of ZSM-5 and other aluminium zeolites. These borosilicate catalysts contain less than 10 ppm Al. 

Tremolite Borosilicate glass Aluminium silicate glass... 

The combustion apparatus consists of a silica or boronfree glass 500 ml Erlenmeyer flask constructed of suitable glass (see Method 2.2). Into the stopper is fused one end of a length of platinum wire, 1 mm in diameter, to the free end of which is attached a piece of 36 mesh platinum gauze, 1.5 cm x 2 cm to act as a sample holder. The flask shall be essentially free from boron and aluminium. Low results are obtained using borosilicate glass flasks. 

The coagulation of hydrolysed aluminium salts has been studied using A1 NMR spectroscopy. The hydrolysis of mixed solutions of Al , Ga ", Ln , and Zr" has been studied by Al and Ga NMR spectroscopy. A C and A1 NMR study of the interaction between Al and tiron, salicylic acid, and phthaUc add has been reported. B, A1, and Si NMR studies of the temperature dependent structural changes in borate, borosilicate, and boro-aluminate Uquids have been reported. The interaction of aluminosilicates by HF has been investigated. Aluminium in polysilicic acid has been speciated using A1 NMR spectroscopy. C, A1 and P NMR spectroscopy has been used to study the formation of Al-NTA-phosphate complexes. The selfdiffusion coefficients of the ATP complex of Al have been studied by H and P pulsed-field gradient NMR spectroscopy. H NMR spectroscopy has been used to study the interaction of Al with phosphatidylcholine vesicles. ... 

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