Mesoporous molecular sieve

Recently, important efforts have been focused on obtaining materials with higher pore sizes [62], for example, the so-called mesoporous molecular sieves (MMS) [63-66], 

The Physical Chemistry of Materials Energy and Environmental Applications 

FIGURE 6.14 Adsorption isotherm of N2 at 77K on a mesoporous molecular sieve, MCM-41 ( , adsorption branch , desorption branch). 

Specifically, pore condensation represents a confinement-induced shifted gas-liquid-phase transition [20], This means that condensation takes place at a pressure, P, less than the saturation pressure, of the fluid [2,4,5], The x = P/P0 value, where pore condensation takes place, depends on the liquid-interfacial tension, the strength of the attractive interactions between the fluid and pore walls, the pore geometry, and the pore size [20], 

Subsequently, it is assumed that for pores of a given shape and surface chemistry, there exists a one-to-one correspondence, between the condensation pressure and the pore diameter. Thus, adsorption isotherms contain unequivocal information about the PSD of the sample under analysis [2,20,41], 

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Kresge C T, Leonowicz M E, Roth W J, Vartuli J C and Beck J S 1992 Ordered mesoporous molecular sieves synthesized by a liquid-crystal template mechanism Nature 359 710-12... 

Third Concept in Catalyst Design. Fenton Detemplation. Mild Organic Template Removal in Micro- and Mesoporous Molecular Sieves... 

Kokufuta, E Jinbo, E, A Hydrogel Capable of Facilitating Polymer Diffusion through the Gel Porosity and Its Application in Enzyme Immobilization, Macromolecules 25, 3549, 1992. Kresge, CT Leonowicz, ME Roth, WJ Vartuli, JC Beck, JS, Ordered Mesoporous Molecular Sieves Synthesized by a Liquid-Crystal Template Mechanism, Nature 359, 710, 1992. 

Corma, A. 1997 From microporous to mesoporous molecular sieve materials and their use in catalysis. Chem. Rev. 97, 2373. 

A fascinating area is micellar autocatalysis reactions in which surfactant micelles catalyse the reaction by which the surfactant itself is synthesized. Thus synthesis of dimethyldoceylamino oxide (reaction between dimethyl dodecyl amine and H2O2) benefits from this strategy. Here an aqueous phase can be used and an organic solvent can be avoided. Synthesis of mesoporous molecular sieves benefit through micellar catalysis and silicate polymerization rates have been increased by a factor 2000 in the presence of cetyltrimethyl ammonium chloride (Rathman, 1996). 

Multifrequency EPR spectroscopy was applied to study Fe(III)-MCM-41 mesoporous molecular sieves with incorporated carotenoids (Konovalova et al. 2003). 

Hartmann, M., A. Piippl et al. (1996). Ethylene dimerization and butene isomerization in nickel-containing MCM-41 and A1MCM-41 mesoporous molecular sieves An electron spin resonance and gas chromatography study. J. Phys. Chem. 100 9906-9910. 

Prakash, A. M., H. M. Sung-Suh et al. (1998). Electron spin resonance evidence for isomorphous substitution of titanium into titanosilicate TiMCM-41 mesoporous molecular sieve. J. Phys. Chem. B 102 857-864. 

Volume 117 Mesoporous Molecular Sieves 1998 Proceedings of the 1st International Symposium, Baltimore, MD, U.S.A., July 10-12, 1998 edited by L. Bonneviot, F. Beland, C. Danumah, S. Giasson and S. Kaliaguine... 

Olson, D.H., Sheppard, E.W., McCullen, S.B., Higgins, J.B. and Schlenker, J.L. (1992) A new family of mesoporous molecular-sieves prepared with liquid-crystal templates. Journal of the American Chemical Society, 114, 10834-10843. 

The mesoporous molecular sieve SBA-15 has been functionalized with aminopropyl moieties via grafting. Further treatment of the 3-aminopropyl-modified material with glutardialdehyde (GA) results in GA-ATS-SBA-15. The modified silica materials were characterized by NMR and IR spectroscopy as well elemental analysis confirming the successful modification. Furthermore, the elemental analysis suggests that two of three amino moieties of the 3-aminopropyl modified material react further with... 

Hydroisomerization of n-octane over Pt-containing micro/mesoporous molecular sieves... 

The development of composite micro/mesoporous materials opens new perspectives for the improvement of zeolytic catalysts. These materials combine the advantages of both zeolites and mesoporous molecular sieves, in particular, strong acidity, high thermal and hydrothermal stability and improved diffusivity of bulky molecules due to reduction of the intracrystalline diffusion path length, resulting from creation of secondary mesoporous structure. It can be expected that the creation of secondary mesoporous structure in zeolitic crystals, on the one hand, will result in the improvement of the effectiveness factor in hydroisomerization process and, on the other hand, will lead to the decrease of the residence time of products and minimization of secondary reactions, such as cracking. This will result in an increase of both the conversion and the selectivity to isomerization products. 

The review of Notari (33) covers the synthesis methodologies of titanium silicate molecular sieves available up to 1996. The reviews of Corma (279) and subsequently of Biz and Occelli (280) describe the synthesis of mesoporous molecular sieves. An informative article on the preparation of TS-1 was reported recently by Perego et al. (68). In this section we list some of the recent developments in the synthesis of micro and mesoporous titanosilicate molecular sieves. 

Metal/zeolite, metal/mesoporous molecular sieves, and metal/mineral catalysts... 

In 1992, Mobil reported a novel family of molecular sieves known as the M41S materials that established an entirely new area in nanoporous solids (168,169). The M41S materials expanded the range of pore sizes into the mesoporous domain (20-300 A). The impact of this discovery on molecular sieve research has been profound. In 1998, an international conference solely devoted to mesoporous molecular sieves was founded (170). The journal Microporous Materials even re-... 

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