Clays pillaring

Fig. 4. Acid strength distribution for the clays pillared with oxide sols heated at 500°C O, TiOo F3, Si02 TiO A. Si02-Feo03 pillared clays.

Clays-pillared clays or organoclays 2D, 3D varies Purification and ion exchange by surfactants of naturally occurring products or synthesis Weeks to months Interlayer distance could be varied and precisely determined X-ray diffraction measurements particles could be grown in situ or incorporated between layers complex supramolecular architecture was possible 478,480,482... 

The above examples of shape selective reactions show the complexity of such systems and that several factors need to be considered before shape selective control can be realized. The use of other porous supports besides zeolites such as carbon molecular sieves, clays, pillared clays and related materials to catalyze shape selective reactions appears to be growing. Molecular modeling of the spatial constraints of various pores is also an area of increased research effort. 

Nanoporous materials like zeolites and related materials, mesoporous molecular sieves, clays, pillared clays, the majority of silica, alumina, active carbons, titanium dioxides, magnesium oxides, carbon nanotubes and metal-organic frameworks are the most widely studied and applied adsorbents. In the case of crystalline and ordered nanoporous materials such as zeolites and related materials, and mesoporous molecular sieves, their categorization as nanoporous materials are not debated. However, in the case of amorphous porous materials, they possess bigger pores together with pores sized less than 100 nm. Nevertheless, in the majority of cases, the nanoporous component is the most important part of the porosity. 

The book explores various examples of these important materials, including perovskites, zeolites, mesoporous molecular sieves, silica, alumina, active carbons, carbon nanotubes, titanium dioxide, magnesium oxide, clays, pillared clays, hydrotalcites, alkali metal titanates, titanium silicates, polymers, and coordination polymers. It shows how the materials are used in adsorption, ion conduction, ion exchange, gas separation, membrane reactors, catalysts, catalysts supports, sensors, pollution abatement, detergency, animal nourishment, agriculture, and sustainable energy applications. 

Adsorption by Clays, Pillared Layer Structures and Zeolites... 

An equivalent surface area of 460 m g was determined from the monolayer volume, Vj. The value obtained for the dimensionless energetic constant, C=260, was characteristic of a microporous material. Although the BET surface area may not be a physically precise quantity due to the fact that the nitrogen molecule does not exhibit the same cross-sectional area in a microporous environment as on a flat surface, the BET value is useful for comparisons of relative porosities among a related class of adsorbents. For instance, smectite clays pillared by metal oxide aggregates typically exhibit BET surface areas in the range 150 - 400 m /g. Thus, the TSLS complex is among the more porous intercalated nanocomposites derived from smectite clays. 

The catalysts used in this study were a zeolite (Zeocat HY 510, Si/Al = 10), a Montmorillonite clay pillared with Titanium species and cationic ion-exchange resins a macroporous lER Amberlyst 15 (Rohm Haas) and resins with a gel structure (K1481 -Bayer and Amberlyst 31 - Rohm Haas). 

In this paper we would like to communicate the details of our investigation in the acylation of 2-MON with acetic anhydride using different solid acid catalysts such as zeolites, clays, pillared clays, unsupported heteropoly acids (HPA) and HPA/KIO, sulphated zirconia euid ion-exchange resins. 

Amount of surfactant (mmol/meq), aluminium adsorbed (mg/g of clay), pillar density number (PDN), 001 spacings (pillared clay catalyst samples. 

Triphasic systems involving clays pillared with surfactants as catalysts offer versatile routes to a range of useful benzylic compounds.40 By using the organo-clay assemblies with sodium cyanide, thiocyanate and hydroxide, it is possible to prepare benzonitriles, benzyl thiocyanates and benzyl alcohols from the corresponding benzyl chlorides. Most of these reactions occur in yields of ca. 80%. 

Structural investigations of clays pillared by the (Ali ) cation using Si and Al NMR were reviewed in 1988 6. Results included in that review will be briefly covered here. 

Figure 4 Schematic flowsheet of clay pillaring process. (From Ref. 1.)...

Heating stage XPS is an ideal technique to study the preparation of pillared clays. Pillared clays are porous heterogeneous catalysts prepared by propping apart the individual clay layers with the help of a large inorganic complex [52], Calcination at an appropriate temperature converts the inorganic complex into... 

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