Synthesis of Porous Materials

Although traditional synthetic methods can be used for preparing a variety of porous materials, the development of template synthesis strategies has prompted an explosive-like growth of synthetic methods. Template synthesis roughly involves the use of a structure-directing reagent that facilitates the porous material to adopt the desired structure, followed by the template release. Three main types of templates, soft, hard, and complex, can be used (Zhao, 2006). 

Soft templates, usually molecules and molecular associations such as amines, thermolabile organic polymers, and surfactants, can be removed by heat treatment. In addition, vesicles, ionic liquids, self-assembled colloidal crystals, and air bubbles have been used for soft templating synthesis. 

Hard templates, whose release requires acid or basic attack such as zeolites and mesoporous silica, used as templates for porous carbon preparation (Kim et al., 2003 Yang et al., 2005), can be taken as examples. 

Complex templates combine soft and hard template techniques. This methodology is used for synthesizing hierarchically bimodal and trimodal meso-macroporous materials with interconnected pore channels combining a surfactant template with a colloidal crystal template (Yuan and Su, 2004). 

In parallel, sol-gel technologies have contributed to a signihcant growth of synthetic procedures for preparation of all types of materials (Wright and Sommerdijk, 2000). 

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Synthesis of Porous Materials Zeolites, Clays, and Nanostructures, edited by Mario L. Occelli and Henri Kessler Methane and Its Derivatives, Sunggyu Lee... 

Sudhakar Reddy, J., Dicko, A., and Sayari, A., in Synthesis of Porous Materials Zeolites, Clays and Nanostructures (M. Occelli and H. Kessler, Eds.), p. 405-415. Marcel Dekker, New York, 1997. 

Synthesis of Porous Materials Zeolites, Clays, and Nanostructures,... 

G. Schulz-Ekloff, J. Rathousky and A. Zukal, in Synthesis of Porous Materials., M. 

Of special significance in the development of PMO materials was the synthesis of porous materials with crystalline order of the bridged silsesquioxane inside the framework walls, initially achieved through the use of tt-tt interactions between 1,4-phenylene-bridged silsesquioxane precursors.33 Molecular scale periodicity in... 

M.L. Occelli and Kessler, (editors), Synthesis of Porous Materials, Marcel Dekker, New York, 1997. 

The synthesis of ordered mesoporous materials in the past decade greatly expanded the range of ordered porous materials and opened up many new opportunities in the design and applications of materials. Of particular importance is the synthetic methodology that is used for the preparation of these materials. Prior to this, the synthesis of porous materials generally involved the use of individual molecules or hydrated clusters of simple ions. In the synthesis of ordered mesoporous materials, however, it is the assembly of surfactant molecules that directs the condensation of inorganic precursors. 

Shkadinskii, K. G., Shkadiskaya, G. V., Matkowsky, B. J., and Volpert, V. A., Self-compaction or expansion in combustion synthesis of porous materials. Combust. Sci. Tech., 88,271 (1992b). 

Mesoporous molecular sieves materials5-8 designated M41S (which include the MCM-41 class of materials) have made a further major impact on the area of synthesis of porous materials. A variety of open framework structures that are mesoporous have recently been reviewed by Thomas.9 Activated charcoal, MCM-41, mesoporous tungsten oxide, and substituted MCM-41 materials are mentioned. This article primarily emphasizes potential applications of such materials and possible mechanisms of reaction. The mesoporous sysems are compared briefly to microporous materials such as zeolites, ALPOs, MeALPOs and SAPOs. 

In R sia many researchers focused their efforts on the development of technology for the synthesis of porous materials from hydrolytic lignin, and certain results have been achieved in the field. According to some publications, not only common sorbents production was tried to solve environmental problems [7,S], but also the synthesis of soibents for special purposes, in particular for gas mixtures separation [9]. 

The selective reduction of steroid ketones by means of LiAlH4-activated template polymers can be carried out following the principle of an ion exchanger. Although the application of polymers in template syntheses is currently limited, and the reactions do not always run satisfactorily, this method appears to be a landmark for future rational syntheses. Microporous phases with three-dimensional lattice networks and defined pore structures and sizes can be obtained by the use of molecules or hydrated ions of alkali metals or alkaline earth metals as templates [73]. A concept developed by the Mobil Oil Company for the synthesis of porous materials employs a regular arrangement of molecules formed... 

E.A. Vasil eva, et al., Specific features of the synthesis of porous materials based on a magnesium-aluminum spinel. Glass Pltys. and Chem. 29(5), 490-493 (2003). 

Occelli, Kessler (Eds) 1997 Synthesis of porous materials (symposium proceedings) [27]... 

Finally, w/c and c/w PFPE based emulsions have been used for the synthesis of porous materials, which are the skeletal replica of the emulsions after removal of the internal phase. W/c microemulsions allowed for macroporous polyacrylate monoliths to be produced (80-82). Conversely, c/w emulsions may be used for the preparation of well-defined porous hydrophilic polymers (83). 

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