Mesostructures

Vanden Bout D A, Kerimo J, Higgins D A and Barbara P F 1997 Near-field optical studies of thin-film mesostructured organic materials Acc. Chem. Res. 30 204-12... 

Higgins D A, Vanden Bout D A, Kerimo J and Barbara P F 1996 Polarization-modulation near-field scanning optical microscopy of mesostructured materials J. Chem. Phys. 100 13 794-803... 

ELECTRO ANALYSIS WITH MESOSTRUCTURED ORGANO-SILICAS... 

Many studies on template thermal degradation have been reported on zeolites of industrial interest including ZSM5 [1-5], silicalite [1], and beta [6-8], as well as surfactant-templated mesostructured materials [9-13]. The latter are structurally more sensitive than molecular sieves. Their structure usually shrinks upon thermal treatment. The general practice is slow heating at 1 °C min (N2/air) up to 550 °C, followed by a temperature plateau. 

Most of the microporous and mesoporous compounds require the use of structure-directing molecules under hydro(solvo)thermal conditions [14, 15, 171, 172]. A serious handicap is the application of high-temperature calcination to develop their porosity. It usually results in inferior textural and acidic properties, and even full structural collapse occurs in the case of open frameworks, (proto) zeolites containing small-crystalline domains, and mesostructures. These materials can show very interesting properties if their structure could be fully maintained. A principal question is, is there any alternative to calcination. There is a manifested interest to find alternatives to calcination to show the potential of new structures. 

Monnier, A Schuth, F Huo, Q Kumar, D Margolese, D Maxwell, RS Smcky, GD Krish-namurty, M Petroff, P Firouzi, A Janicke, M ChmeUca, BE, Cooperative Formation of Inorganic-Organic Interfaces in the Synthesis of Silicate Mesostructures, Science 261, 1299, 1993. 

Proceedings of the Fourth Tokyo Conference on Advanced Catalytic Science and Technology, Tokyo, July 14-19, 2002 edited by M. Anpo, M. Onaka and H. Yamashita Volume 146 Nanotechnology in Mesostructured Materials... 

Fig. 11 Pore size distributions and TEM images of ZrOi 4Si02 materials formed from Zr[OSi(O Bu)3]4. The upper portion shows a xerogel and the bottom portion shows a mesostructured material...

Pt particles remain highly dispersed in the reaction mixture during mesostructure formation. All measurements including XRD, SAXS, and TEM indicate a well-ordered silica structure. N2 physisorption measurement indicated high surface areas (523-661 m g ) and meso-sized pores (112-113 A) for the silica supports produced in the presence of different Pt particles. 

Porous Membranes of Nanoparticies from Templating Against AAO Membranes Using LB Technique. AAO-porous substrate has broad applications in making metal and semiconductor nanowires, aligned mesostructured nanorods, inorganic nanotubes. 

Proceedings of the 3rd International Mesostructured Materials Symposium, Jeju, Korea, July 8—11, 2002... 

Figure 4.18 TEM images showing the mesostructures of Ti02 species dispersed in Si02 transparent thin films with (a) a hexagonal ordered pore arrangement and (b, c) cubic symmet7. Reproduced from [247] (2003) with permission from Elsevier.

Most of the supports so far studied are conventional in the field of catalysis. Some new kinds of support have emerged including mesostructured materials,193 dendrimers, organic-inorganic hybrids, and natural polymers such as polysaccharides or polyaminoacids. Nevertheless, at the moment, supported catalysts still suffer from relatively poor stability when compared to classical heterogeneous catalysts, and from limited activity when compared to homogeneous catalysts. The driving force for this research is thus to make up some of these deficits. 

Fig. 2.18 Vesicle structures with silica wall (A) mesostructured silica vesicle (B) hollow capsule composed of silica particles prepared by LbL assembly.

Fig. 4.19 Preparation of a protein-like structure in an inorganic mesostructured framework (Proteosilica) as a transparent film using polypeptide-functionalized surfactants.

Fowler, C.E., Khushlani, D. and Mann, S. (2001) Interfacial synthesis of hollow microspheres of mesostructured silica. Chemical Communications, 2028-2029. 

Fig. 10.14 Schematic representation of the membrane = 47 mm), mesostructured silica-synthetic route to dynamic functionalized me- surfactant before (B) and after (C) calcination, sostructured silica membranes in the AAMs ODS-hydrophobized silica before (D) and after...

Bose, F., Ayral, A., Albouy, P.A., Datas, L. and Guizard, C. (2004) Mesostructure of anatase thin films prepared by mesophase templating. Chemistry of Materials, 16 (11), 2208-2214. 

Mesostructured materials with adjustable porous networks have shown a considerable potential in heterogeneous catalysis, separation processes and novel applications in optics and electronics [1], The pore diameter (typically from 2 to 30 nm), the wall thickness and the network topology (2D hexagonal or 3D cubic symmetry) are the major parameters that will dictate the range of possible applications. Therefore, detailed information about the formation mechanism of these mesostructured phases is required to achieve a fine-tuning of the structural characteristics of the final porous samples. 

XRD patterns and data from table 1 confirm the ordered 2D (P6mm) mesostructure of SBA-15 and Al-SBA-15 whatever the synthesis method. 

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