Aluminosilicate Catalyst

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 general principle usually involves contact of an aldehyde or mixtures of aldehydes with ammonia at high temperature in the presence of an acidic catalyst. Aluminosilicate catalysts have been used (80USP4220783). A series of condensation reactions occurs with elimination of water and hydrogen and mixed products usually result. Acetaldehyde gives... 

Aluminum (properly called aluminium, but the former name prevails in North America) is found in combination with Si and 0 as aluminosilicates in rocks, and as its ore, bauxite. The metal finds use in vehicles, aircraft, packaging, cookware, construction materials, etc., while aluminum salts are used in baking powders, water treatment, and dyeing of textiles. Aluminum oxide is widely used as a refractory and as a support for catalysts. Aluminosilicate catalysts such as zeolites are of key importance in the chemical and petroleum industries. 

Zeolite A [1318-02-1] Zeolite (aluminosilicate) Zeolite catalysts Zeolite L Zeolites... 

Remarkably, seventy years after Houdry s utilization of the catalytic properties of activated clay and the subsequent development of ci ystalline aluminosilicate catalysts that arc a magnitude more catalytically active, the same fundamental principles remain the basis for the modern manufacture of gasoline, heating oils, and petrochemicals. 

Typical conditions for the disproportionation reaction are 450-530°C and 20 atmospheres. A mixture of C0O-M0O3 on aluminosilicates/alumina catalysts can he used. Conversions of approximately 40% are normally used to avoid more side reactions and faster catalyst deactivation. The equilihrium constants for this reaction are not significantly changed hy shifting from liquid to vapor phase or hy large temperature changes. 

Microporous catalysts are heterogeneous catalysts used in catalytic converters and for many other specialized applications, because of their very large surface areas and reaction specificity. Zeolites, for example, are microporous aluminosilicates (see Section 14.19) with three-dimensional structures riddled with hexagonal channels connected by tunnels (Fig. 13.38). The enclosed nature of the active sites in zeolites gives them a special advantage over other heterogeneous catalysts, because an intermediate can be held in place inside the channels until the products form. Moreover, the channels allow products to grow only to a particular size. 

Zeolites form a unique class of oxides, consisting of microporous, crystalline aluminosilicates that can either be found in nature or synthesized artificially [J.M. Thomas, R.G. Bell and C.R.A. Catlow in Handbook of Heterogeneous Catalysis (Ed. G. Ertl, H. Knbzinger and J. Weitkamp) (1997), Vol. 1, p. 206, VCH, Weinheim.]. The zeolite framework is very open and contains channels and cages where cations, water and adsorbed molecules may reside and react. The specific absorption properties of zeolites are used in detergents, toothpaste, and desiccants, whereas their acidity makes them attractive catalysts. 

The intercalates of sheet aluminosilicates (clays) and of graphite are demonstrated to be efficient catalysts for a variety of reactions, and results obtained using several analytical techniques, including magic angle spinning KMR, are presented. For the clay family,... 

This i>aper describes two broad types of intercalation conpomds which are based on graphite on the one hand and sheet aluminosilicate (clay) hosts on the other. Taken together these provide a rich veiriety of examples of heterogeneously catalysed reactions. Appropriately cation exchanged clays, for example, act as efficient catalysts for a number of commercially important proton catalysed reactions (10-13) (see Table I). Graphite intercalates, whilst also capable of... 

The hydroamination of alkenes has been performed in the presence of heterogeneous acidic catalysts such as zeolites, amorphous aluminosilicates, phosphates, mesoporous oxides, pillared interlayered clays (PILCs), amorphous oxides, acid-treated sheet silicates or NafioN-H resins. They can be used either under batch conditions or in continuous operation at high temperature (above 200°C) under high pressure (above 100 bar). 

The liquid-phase autoxidation of cyclohexane is carried out in the presence of dissolved cobalt salts. A lot of heterogeneous catalysts were developed for this process but most catalysts lacked stability. The incorporation of cobalt ions in the framework of aluminophosphate and aluminosilicate structures opens perspectives for heterogenization of this process. CoAPO (cobalt aluminophosphate) molecular sieves were found to be active heterogeneous catalysts of this oxidation.133 Site isolation was critical to get active catalysts.134... 

Zeolites are hydrous aluminosilicates that are widely used as catalysts in the chemical process industry. Zeolite A is usually synthesized in the sodium form from aqueous solutions of sodium... 

MCM-22 zeolite (IZA code MWW) presents a novel and original structure which is composed of two independent pore systems a 2-dimensional, sinusoidal, 10-ring intralayer channels system and an interlayer system with 12-ring supercages, accessible through 10-ring apertures [1], This unique pore structure of the aluminosilicate MCM-22 zeolites makes them interesting catalysts for a wide variety of acid-catalyzed reactions, e.g. alkylation of aromatics [2],... 

Multiwall carbon nanotubes (MWCNTs) have been synthesized by catalytic chemical vapor deposition (CCVD) of ethylene on several mesoporous aluminosilicates impregnated with iron. The aluminosilicates were synthesized by sol-gel method optimizing the Si/Al ratios from 6 to 80. The catalysts are characterized by nitrogen adsorption, X-ray diffraction, 27A1 NMR, thermogravimetric analysis (TGA) and infrared. The MWCNTs are characterized by TGA and transmission and scanning electron microscope. 

Figure 4 shows TEM images of CNT synthesized by using aluminosilicates. The results show that A1 incorporated in mesoporous silica reduces considerably the quantity of amorphous carbon, increasing the catalyst selectivity. The Fe/Al-MCM41 (10) shows the MWCNTs with the highest purity (98%), an average diameter of 40 nm and the lowest quantity of amorphous carbon. 

In this chapter, we demonstrate the potential of such agents as catalysts/promoters in key steps for the derivatization of sugars. The most significant catalytic approaches in carbohydrate chemistry that use aluminosilicate porous materials, namely zeolites and montmorillonite clays, are reviewed and discussed. Silica gel is a porous solid silicate that has also been used for heterogeneous catalysis of organic reactions in general. We include here its usefulness as promoter and reagent support for the reactions under consideration. 

Houdry The first catalytic petroleum cracking process, based on an invention by E. J. Houdiy in 1927, which was developed and commercialized by the Houdry Process Corporation. The process was piloted by the Vacuum Oil Company, Paulsboro, NJ, in the early 1930s. The catalyst was contained in a fixed bed. The first successful catalyst was an aluminosilicate mineral. Subsequently, other related catalysts were developed by Houdry in the United States, by I. G. Farbenindustrie in Germany, and by Imperial Chemical Industries in England. After World War II, the clay-based catalysts were replaced by a variety of synthetic catalysts, many based on alumino-silicates. Later, these too were replaced by zeolites. U.S. Patents 1,837,963 1,957,648 1,957,649. 

Isocracking A hydrocracking process developed and licensed by Chevron Research Company. The catalyst is nickel or cobalt sulfide on an aluminosilicate. First commercialized in 1962 more than 45 units had been built by 1994. See also Isomax. 

Kombi [Kombinations-Verfahren] A liquid-phase petroleum hydrogenation process which combined hydrogenation with hydrorefining. The catalyst contained molybdenum and tungsten on an aluminosilicate. Developed by BASF. 

The FPI principle can also be used to develop thin-film-coating-based chemical sensors. For example, a thin layer of zeolite film has been coated to a cleaved endface of a single-mode fiber to form a low-finesse FPI sensor for chemical detection. Zeolite presents a group of crystalline aluminosilicate materials with uniform subnanometer or nanometer scale pores. Traditionally, porous zeolite materials have been used as adsorbents, catalysts, and molecular sieves for molecular or ionic separation, electrode modification, and selectivity enhancement for chemical sensors. Recently, it has been revealed that zeolites possess a unique combination of chemical and optical properties. When properly integrated with a photonic device, these unique properties may be fully utilized to develop miniaturized optical chemical sensors with high sensitivity and potentially high selectivity for various in situ monitoring applications. 

The immobilization of catalysts on a solid support is a well-known approach to render a system recycleable, and this has been performed recently by the immobilization of rhodium-MonoPhos 29 a on aluminosilicate A1TUD-1. The resultant system showed high efficiency in water, and could be recycled [80]. 

---