Layered silicates, intercalation molecular catalysts

Pillared clays, layered silicates whose sheets have been permanently propped open by thermally stable molecular props, were used as templates to load various organic precursors.The pore diameters of resulting carbon materials range from 8 to 22 A, and the mass fractal dimension varies from 2.5 to 2.9, which are accessible to lithium ions when the intercalation process takes place in a lithium secondary battery. An approach to pyrolyse aromatic hydrocarbons such as pyrene within a pillared clay was also reported, in which the pillared clay serves two functions.It acts as the inorganic template around which the carbon can be formed, and it also functions as an acid catalyst to promote condensation of the aromatics similar to the Scholl reaction. The resulting carbon materials have pore sizes from 15 to 50... 

Alexandre et al. [98] reported the preparation of PE/clay nanocomposite using Ti-based constrained geometry catalyst (CGC) catalyst. The MMT and hectorite were initially treated with TMA-depleted MAO and then intercalated with the CGC catalyst. Finally, addition of ethylene resulted in the formation of high molecular weight and exfoliated PE/clay nanocomposites. The vinyl groups were chemically linked to the sDicate surface when copolymerized was carried out with ethylene inside the clay galleries using the nickel catalyst (Fig. 9). This method not only results in the effective exfoliation of the layered silicate but also in polyethylene chains that are chemically bonded to silicate surface. 

In principle, all the kinetic concepts of intercalation introduced for layer-structured silicates hold for zeolites as well. Swelling, of course, is not found because of the rigidity of the three dimensional frame. The practical importance of zeolites as molecular sieves, cation exchangers, and catalysts (cracking and hydrocracking in petroleum industry) is enormous. Molecular shape-selective transport (large differences in diffusivities) and micro-environmental catalysis (in cages and channels)... 

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