Pillared clay minerals

Fig. 2 Scheme for recycling surfactant-modified pillared clay mineral adsorbents during thermal treatment of toxicant. From Michot and Pinnavaia (1991), with kind permission from the Clay Minerals Society. 

Bradley, S.M. and Kydd, R.A., 1991. A Comparison of the Thermal Stabilities of Gaj3, GaAlj2 and AIj3 Pillared Clay Minerals. Catalysis Letters, 8 185. 

Figure 3. PowdCT X-ray diffiraction pattrans of the AI13, Gai3 and GaAli2 pillared clay minerals, (a) after drying at room temperature, (b) after heating at 700f C for 12 hours.

Pillaring is the process by which an inorganic layered compound is transformed into a thermally stable micro- and mesoporous material with retention of the layer structure. The pillared material is a pillared layered solid, or PLS. In the case of clay minerals, one obtains a pillared clay mineral. A PLS is a subgroup of the group of intercalation compounds, which meet the following criteria (1) ... 

Table 5 Adsorption Properties of Al-Pillared Clay Minerals...

Occelli, M. L. (1984) Sorption of Normal Paraffins in a Pillared Clay Mineral. Proceedings 8th International Congress in Catalysis 4, 725. 

Pillared clays are smectite minerals or iUite-smectite minerals that have been stmcturaHy modified to contain pillars of stable inorganic oxide. The pillars prop open the smectite stmcture so they have a basal space of approximately 3.0 nm. Typical metals in the pillars include Al, Zr, Ti, Ce, and Fe, and these materials are used in catalytic processes to crack heavy cmde oils (110—112). 

Bergaya F, Aouad A, Mandalia T (2006) Pillared clays and clay minerals. In Bergaya F, Theng BKG, Lagaly G (eds) Handbook of clay science. Elsevier,... 

The aged pillaring reagents were heated to 65 C and 325 bentonite, American Colloid Company, whose major constituent is the layered clay mineral, montmorilIonite, was added. There was always a 5-fold excess of aluminum in solution and the volume of solution per gram of clay was always 45 cc/g or more. The reaction was carried out for 2 hours. The slurry was filtered and the solids washed two times with water, dried, sized, and calcined at 500 C for 2 hours in air. 

Thermally pillared clays Dimerization of unsaturated fatty acids to dimer acids Removal of olefins from BTX , ethylbenzene, cumene, etc. steams Decolonization of industrial oil derivatives Purification of kerosene and other mineral oil derivatives... 

Future EXAFS studies of the local structure of reactive sites in pillared clay derivatives and related hydroxy-interlayered clay minerals should help elucidate the reactivity of these materials as catalysts for synthetic organic chemical conversions, as well as for reactions occurring in the natural soil environment. 

Recent advances in this technology include the use of 2 1 clays converted to hydrophobic forms through the introduction of surfactants in the interlayer. For example, Boyd et al. (1991) introduced cationic chain surfactants into 2 1 clay minerals. Such clays were demonstrated to have high affinity for hydrophobic organic chemicals. Additionally, polyethylene oxides (PEOs) have been intercalated into aluminum-pillared montmorillonite (Montarges et al., 1995). Because PEOs have a... 

Bergaya, F., A. Aouad, and T. Mandalia. 2008a. Pillared clays and clay minerals. In Handbook of clay science, 3rd ed., ed. F. Bergaya, B. K. G. Theng, and G. Lagaly, 393-421. Amsterdam Elsevier. 

The pillared and nanoparticle-containing montmorillonites open up new venues for the application of clay minerals in organic syntheses and production of composite materials. 

Drame, H. 2005. Cation exchange and pillaring of smectites by aqueous Fe nitrate solutions. Clays Clay Miner. 53 335-347. 

Bentonite, whose main ingredient is montmorillonite, is one kind of layer structure clay mineral. It is an ideal material for preparation of pillared clays. If metal cations with high catalytic activity were intercalated in the interlayers of montmorillonite, a new type of solid acid catalyst can be obtained. The catalytic activity of the catalyst is closely associated with its porosity, specific surface area and surface total acidity. One of the effective ways to enhance catalytic activity is to prepare catalyst with appropriate metal cations and structure. 

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